Wiley Acta Medica Okayama 0919-8172 2025 Daytime Bladder Control Status in Toddlerhood Is Associated With Subsequent Bedwetting in Preschool Years: A Nationwide Cohort Study of Over 30 000 Japanese Children EN Takatoshi Moriwake Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Naomi Matsumoto Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yusuke Tominaga Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kensuke Uraguchi Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoko Kobayashi Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Ichiro Tsuboi Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kasumi Yoshinaga Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoaki Yamanoi Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tatsushi Kawada Department of Urology Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Okayama Japan Takuya Sadahira Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Satoshi Katayama Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takehiro Iwata Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Shingo Nishimura Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kensuke Bekku Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kohei Edamura Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Soshi Takao Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Motoo Araki Department of Urology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Objectives: Nocturnal enuresis is common in early childhood. While daytime bladder control typically precedes nighttime continence, the temporal relationship between early daytime bladder control and subsequent bedwetting remains unclear. We investigated whether daytime bladder control status at age 2.5 years―as indicated by diaper use―is associated with bedwetting at age 4.5 years in a Japanese nationwide cohort. Methods: We analyzed data from the Japanese Longitudinal Survey of Newborns in the 21st Century (2010 cohort). Daytime bladder control was assessed at age 2.5 years through caregiver-reported diaper use, and bedwetting frequency at age 4.5 years through parental questionnaires. Modified Poisson regression estimated risk ratios (RRs), adjusting for birth-related factors, socioeconomic status, daycare attendance, and developmental milestones. Results: Among 32 168 children, 26 651 (82.8%) still used diapers at 2.5 years. Bedwetting prevalence at 4.5 years was 42.2%: 34.5% in children who achieved daytime bladder control at 2.5 years versus 43.9% in those still using diapers. After multivariable adjustment, incomplete daytime bladder control at 2.5 years was associated with higher bedwetting risk (adjusted RR 1.25; 95% CI, 1.20–1.31). Multinomial regression revealed dose–response relationships: odds ratios 1.41 (95% CI, 1.30–1.52) for “sometimes” and 1.58 (95% CI, 1.42–1.77) for “often” bedwetting. Conclusions: Daytime bladder control status at 2.5 years was associated with a 25% increased bedwetting risk at 4.5 years. This association likely reflects individual differences in bladder control maturation rather than causal effects. While daytime bladder control may serve as a developmental marker, its validity as an intervention target remains unestablished. No potential conflict of interest relevant to this article was reported.

岡山医学会 Acta Medica Okayama 0030-1558 137 3 2025 備前市における新型コロナウイルス感染症の抗体検査に関する研究の成果報告 118 125 EN Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Science, Okayama University Ayako Sasaki Kurashiki City Public Health Center Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Science, Okayama University Tomoka Kadowaki Center for Public Health Action in Applied Epidemiology, National Institute of Infectious Diseases Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Science, Okayama University 　We conducted two prospective cohort studies (June 2022–March 2023 and Nov 2023–Jan 2024) of 1,899 and 445 residents and other individuals who are affiliated with institutions in the city of Bizen in Japan's Okayama prefecture (population 32,320 as of 2020). We measured the subjects' titers of antibodies against SARS-CoV-2, evaluated changes in their antibody titers, and assessed the associations of the titers with the subjects' vaccination status, infection, and COVID-19 status/severity. This report summarizes the two studies' findings. These prospective studies based on a wide age range in a general population provide information that can be used to determine the appropriate timing of vaccination during a pandemic. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 2045-2322 15 1 2025 Association between gestational age and child health and neurodevelopment in twins from a nationwide longitudinal survey in Japan 40608 EN Kei Tamai Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Akihito Takeuchi Division of Neonatology, NHO Okayama Medical Center Makoto Nakamura Division of Neonatology, NHO Okayama Medical Center Misao Kageyama Division of Neonatology, NHO Okayama Medical Center Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Despite previous research, evidence on the relationship between gestational age and long-term health and neurodevelopmental outcomes among twins remains limited. Using data from the Longitudinal Survey of Babies in the 21st Century, we analyzed 549 twins born in Japan in 2010. The twins were grouped by gestational age: <32 weeks (very preterm), 32–36 weeks (moderately and late preterm), and 37–38 weeks (early term). The health status was evaluated by hospitalization between 0.5 and 5.5 years, and behavioral development was assessed using questionnaires at 2.5 and 5.5 years. Binomial log-linear regression with generalized estimating equations accounted for within-pair correlations and adjusted for child and parental variables. Moderately and late preterm children showed a higher risk of all-cause hospitalization during infancy than early-term children (adjusted risk ratio, 1.7; 95% CI, 1.0–2.6). Very preterm children showed a higher point estimate of the risk ratio, but a wide CI (risk ratio, 2.3; 95% CI, 0.8–6.8). Behavioral delays were more common in preterm groups at 2.5 years but not at 5.5 years. Preterm twins have a higher risk of hospitalization during infancy and developmental delay at 2.5 years than early-term twins. These risks show an increasing trend as gestational age decreases. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 0300-9572 215 2025 Compression only CPR and mortality in pediatric out-of-hospital cardiac arrest during COVID-19 pandemic 110706 EN Takafumi Obara Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Hiromichi Naito Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Kohei Tsukahara Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Takashi Hongo Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Tsuyoshi Nojima Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Tetsuya Yumoto Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Atsunori Nakao Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Background: The COVID-19 pandemic influenced resuscitation practices worldwide, leading to a notable decline in rescue breathing cardiopulmonary resuscitation (RB-CPR), even in pediatric out-of-hospital cardiac arrest (OHCA). Understanding the impact of this decline is important to assess the role of rescue breathing in pediatric resuscitation. This study aimed to evaluate the impact of the reduced RB-CPR during the COVID-19 pandemic on mortality and neurological outcomes among pediatric OHCA patients in Japan. Methods: This retrospective cohort study utilized data from the nationwide All-Japan Utstein Registry for pediatric OHCA patients (≤17 years) who received bystander CPR between January 2017 and December 2021. Data were compared in pre-COVID-19 (2017–2019) versus pandemic (2020–2021) periods. Bystander CPR were classified as RB-CPR or chest compression-only CPR (CO-CPR). The primary outcome was 30-day mortality, with secondary outcomes including the absence of return of spontaneous circulation and unfavorable neurological outcomes (Cerebral Performance Category scores of 3–5). Adjusted risk ratios (aRR) with 95 % confidence intervals (CI) were estimated using Poisson regression. Results: Of 7,162 pediatric OHCA cases, 3,352 (46.8 %) received bystander CPR. RB-CPR decreased from 33.0 % pre-pandemic to 21.1 % during the pandemic. CO-CPR was associated with higher 30-day mortality (aRR: 1.16; 95 % CI: 1.08–1.24) and unfavorable neurological outcomes (aRR: 1.10; 95 % CI: 1.05–1.16). These trends were consistent across age groups and arrest etiologies, particularly for non-cardiac causes. More significantly, the decrease in RB-CPR was estimated to contribute to 10.7 excess deaths annually during the pandemic. Conclusions: The findings highlight the importance of rescue breathing in pediatric OHCA. CO-CPR, while suitable for adults, may compromise outcomes in children. Emphasizing rescue breathing in pediatric resuscitation training and integrating infection control measures is essential for future public health emergencies. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 1328-8067 67 1 2025 Early-life exposures and child health outcomes: A narrative review of LSN21 research in Japan e70258 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Rumi Matsuo Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yuka Yamamura Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takahiro Tsuge Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tomoka Kadowaki Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kensuke Uraguchi Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kei Tamai Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kazue Nakamura Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Akihito Takeuchi Division of Neonatology, NHO Okayama Medical Center Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Background: The Longitudinal Survey of Newborns in the 21st Century (LSN21) tracks two Japanese national birth cohorts―2001 (baseline n = 47,010) and 2010 (n = 38,554)―from infancy through young adulthood, capturing parenting practices and family environments. Most studies analyze single exposures or outcomes. We conducted a narrative review summarizing the findings published by the Okayama University group on diverse health and developmental outcomes. Methods: We reviewed 59 LSN21 papers (2013–2025), extracting data on exposures, outcomes, and methods. Evidence was categorized into four exposure types (infant feeding, sleep, environmental, and perinatal) and three outcome domains (obesity, allergies/respiratory tract infections, and neurobehavioral development), including cohort comparisons. Results: Exclusive breastfeeding was associated with a lower obesity risk at ages 7 (adjusted odds ratio 0.55, 95% confidence interval 0.39–0.78) and 15, later puberty, and fewer hospitalizations. Short or irregular sleep before age 3 was linked to behavioral problems and injuries. Maternal smoking and prenatal air pollution were associated with respiratory conditions and developmental challenges. Preterm birth and small-for-gestational-age predicted delays, especially without catch-up growth by age 2. Pneumococcal vaccination likely contributed to declining otitis media after 2010. Additional findings included associations between outdoor play and reduced obesity risk, and complex relationships between breastfeeding and food allergies that varied by infantile eczema status. Conclusions: LSN21 findings highlight modifiable early-life factors (breastfeeding, sleep patterns, and smoke-free environments) and identify preterm and growth-restricted children for priority monitoring. While LSN21's strength lies in longitudinal social assessments, complementary perspectives from other Japanese cohorts could enhance understanding of biological mechanisms and intergenerational effects. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 1328-8067 67 1 2025 Changes in body mass index during early childhood on school‐age asthma prevalence classified by phenotypes and sex e70090 EN Toshihiko Yabuuchi Department of Pediatrics, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Masanori Ikeda Department of Pediatrics, Okayama University Medical School Naomi Matsumoto Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Mitsuru Tsuge Department of Pediatrics, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hirokazu Tsukahara Department of Pediatrics, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Background: Few studies have explored the relationship between changes in body mass index(BMI) during early childhood and asthma prevalence divided by phenotypes and sex, and the limited results are conflicting. This study assessed the impact of BMI changes during early childhood on school-age asthma, classified by phenotypes and sex, using a nationwide longitudinal survey in Japan. Methods: From children born in 2001 (n = 47,015), we divided participants into BMI quartiles (Q1, Q2, Q3, and Q4) and the following BMI categories: Q1Q1 (i.e., Q1 at birth and Q1 at age 7), Q1Q4, Q4Q1, Q4Q4, and others. Asthma history from ages 7 to 8 was analyzed, with bronchial asthma (BA) further categorized as allergic asthma (AA) or nonallergic asthma (NA) based on the presence of other allergic diseases. Using logistic regression, we estimated the asthma odds ratio (OR) and 95% confidence intervals (CIs) for each BMI category. Results: Q1Q4 showed significantly higher risks of BA, AA, and NA. In boys, BA and NA risks were significantly higher in Q1Q4 (adjusted OR: 1.47 [95% CI: 1.17–1.85], at 1.56 [95% CI: 1.16–2.1]), with no significant difference in AA risk. In girls, no increased asthma risk was observed in Q1Q4, but AA risk was significantly higher in Q4Q4 (adjusted OR: 1.78 [95% CI: 1.21–2.6]). Conclusion: Our results demonstrated that BMI changes during early childhood impact asthma risks, particularly that the risk of NA in boys increases with BMI changes during early childhood, and the risk of AA in girls increases with consistently high BMI. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 2045-2322 15 1 2025 Association between cesarean delivery and childhood allergic diseases in a longitudinal population-based birth cohort from Japan 19206 EN Kei Tamai Department of Epidemiology, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Naomi Matsumoto Department of Epidemiology, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Takashi Mitsui Department of Obstetrics and Gynecology, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Hisashi Masuyama Department of Obstetrics and Gynecology, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Takashi Yorifuji Department of Epidemiology, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine The association between cesarean delivery and childhood allergic diseases, such as atopic dermatitis, food allergy, and bronchial asthma, remains unclear, with limited evidence from Asian populations. We analyzed population-based data of 2,114 children born in Japan in 2010 from the Longitudinal Survey of Babies in the 21st Century, linked to the Perinatal Research Network Database. Comparisons were made between children born by cesarean delivery and those born vaginally. Longitudinal outcomes were atopic dermatitis, food allergy, and bronchial asthma during childhood for each age group up to 9 years of age. We performed Poisson regression analyses with robust variance, and adjusted for child and parent variables, followed by supplementary analyses using generalized estimating equations (GEE). Children born by cesarean delivery did not have a higher risk of most outcomes compared to those born vaginally. GEE analysis found no association between cesarean delivery and atopic dermatitis (adjusted risk ratio [aRR] 0.8, 95% confidence interval [CI] 0.5–1.2), food allergy (aRR 1.1, 95% CI 0.7–1.7), bronchial asthma (aRR 1.0, 95% CI 0.8–1.4), or allergic rhinoconjunctivitis (aRR 0.9, 95% CI 0.8–1.1). This study shows no clear evidence of an association between delivery mode and childhood allergic diseases in Japan. No potential conflict of interest relevant to this article was reported.

Nature Portfolio Acta Medica Okayama 2045-2322 15 1 2025 Cesarean delivery on child health and development in Japanese nationwide birth cohort 2485 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Mitsui Department of Obstetrics and Gynecology, Okayama University Graduate School of Medicine Kei Tamai Division of Neonatology, NHO Okayama Medical Center Tomoya Hirota Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California San Francisco Hisashi Masuyama Department of Obstetrics and Gynecology, Okayama University Graduate School of Medicine Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University The long-term effects of cesarean delivery (CD) on child health and development remain controversial. This study aimed to investigate these effects using an outcome-wide approach in a Japanese context, where perinatal mortality rates are among the world's lowest. We analyzed data from 2,114 children in a nationwide Japanese birth cohort, linking the 21st Century Longitudinal Survey of Newborns with the Perinatal Research Network database. We examined associations between CD and various health and developmental outcomes up to 9 years of age, including hospitalizations, obesity, and developmental milestones. After adjusting for potential confounders, CD was not significantly associated with most outcomes, including all-cause hospitalization (adjusted risk ratio 1.25, 95% CI 0.997-1.56), obesity at 5.5 and 9 years, and various developmental milestones. Subgroup analyses for multiple births and preterm infants showed some differences in point estimates, but were limited by small sample sizes. CD was not significantly associated with adverse long-term child health or developmental outcomes in this Japanese cohort. These findings provide reassurance regarding CD safety when medically indicated in advanced perinatal care settings. Further research with larger samples and longer follow-up is needed, especially for specific subgroups. No potential conflict of interest relevant to this article was reported.

BMC Acta Medica Okayama 1710-1492 21 1 2025 Maternal smoking during infancy increases the risk of allergic diseases in children: a nationwide longitudinal survey in Japan 4 EN Kenji Shigehara Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Mitsuru Tsuge Department of Pediatric Acute Diseases, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Kazuhiro Uda Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Yukie Saito Department of Pediatrics, Okayama University Hospital Masato Yashiro Department of Pediatrics, Okayama University Hospital Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Masanori Ikeda Department of Pediatrics, Okayama University Hospital Hirokazu Tsukahara Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Background The incidence of allergic diseases has been increasing in Japan. In particular, a serious decline in the age of onset of allergic rhinitis has been observed. Passive smoking from parental smoking has a significant impact on children’s health; however, it is difficult to restrict smoking in the home. While various studies have previously reported on the relationship between passive smoking and the development of allergic diseases in children. However, there have been no reports on passive smoking and allergic diseases on a national scale. Methods Using Japanese national longitudinal survey data (n = 38,444) for newborns born between May 10 and 24, 2010, we assessed parental smoking habits when their children were 6 months old and investigated the association with the development of allergic diseases until the age of 5.5 years. The risk ratios and 95% confidence intervals for the development of different allergic diseases were analyzed after adjusting for potential confounders using Poisson regression with a robust error variance. Results The risk ratio for developing allergic rhinitis/allergic conjunctivitis (AR/AC) in children was significantly higher in the maternal smoking groups ( ≦ 10 cigarettes/day; RR 1.15, 95% CI 1.02–1.30; ≧11 cigarettes/day; RR 1.16, 95% CI 0.93–1.44). Furthermore, associations were found between the maternal smoking group in the presence of paternal smoking and the risk of developing bronchial asthma ( ≦ 10, RR 1.33 95% CI 1.17–1.52; ≧11, RR 1.71 95% CI 1.38–2.1), food allergy ( ≦ 10, RR 1.36 95% CI 1.12–1.63; ≧11, RR 1.25 95% CI 0.84–1.86), atopic dermatitis ( ≦ 10, RR 1.42 95% CI 1.22–1.66; ≧11, RR 1.6 95% CI 1.2–2.13), and AR/AC ( ≦ 10, RR 1.21 95% CI 1.07–1.36; ≧11, RR 1.35 95% CI 1.09–1.67). Conclusions Maternal smoking during infancy increases the risk of developing AR/AC in children. Considering paternal smoking, maternal smoking further increased the risk of developing allergic diseases in children, suggesting that reducing parental smoking at home may reduce the risk of developing allergic diseases in children. No potential conflict of interest relevant to this article was reported.

Oxford University Press (OUP) Acta Medica Okayama 1460-2229 2023 Effect of 2-week postpartum check-ups on screening positive for postpartum depression: a population-based cohort study using instrumental variable estimation in Japan cmad074 EN Naoko Nakamura Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Yasuko Nakashima Health Promotion Division, Tsuyama City Department of Children’s Health Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Background: Postpartum depression is experienced by approximately 10% of women and affects the health and development of their children. Although it is recommended that all mothers have the opportunity for early detection and intervention for postpartum depression, it is unclear whether early postpartum check-ups help to reduce postpartum depression. Objective: The aim of this study was to assess the effect of 2-week postpartum check-ups on screening positive for postpartum depression in Japan. Methods: This was a population-based cohort study that used the administrative database of Tsuyama, Japan. Participants were women who received postpartum home visits from a public health nurse in Tsuyama during the fiscal years 2017–2019. Data were obtained on participant’s attendance at a 2-week postpartum check-up and their responses on the Edinburgh Postpartum Depression Scale. Owing to the initiation of a publicly funded postpartum check-up programme, participants were pseudo-randomly assigned to receive/not receive a 2-week postpartum check-up. We conducted instrumental variable estimation to assess the causal effects of the check-up on screening positive for postpartum depression. Results: The characteristics of the 1,382 participants did not differ by fiscal year of childbirth. We found a 6.7% (95% confidence interval 2.2–11.2) reduction in the prevalence of screening positive for postpartum depression as an effect of 2-week postpartum check-ups among women received 1-month postpartum home visits. Conclusion: The results suggest that 2-week postpartum check-ups are effective in reducing the prevalence of screening positive for postpartum depression among 1-month postpartum women. Despite some limitations, early postpartum care could reduce postpartum depression. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 1444-1586 25 1 2024 Impact of high blood pressure on the risk of mortality among Japanese people aged 65 years and older 82 89 EN Shinsuke Akagi Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Rumi Matsuo Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Aim: The purpose of this study is to investigate the impact of abnormal blood pressure on the risk of all-cause and cardiovascular mortality in a large cohort of older Japanese people aged ≥65 years. Methods: This cohort study enrolled 54 760 participants from Okayama City aged ≥65 years who underwent basic health checkups from April 2006 to March 2008. Based on blood pressure, the participants were divided into six categories, from C1 (lowest) to C6 (highest). To assess the association of blood pressure with all-cause and cardiovascular mortality, we used survival analysis to estimate hazard ratios (HRs) for all-cause mortality and subdistribution HRs (SHRs) for cardiovascular mortality on C3. We then repeated the analyses based on age groups (65–74 years, 75–84 years, and ≥85 years). Results: The fully adjusted HRs for all-cause mortality, which included all individual potential confounders, were 1.11 (95% confidence interval [CI]: 1.04–1.19) for C5 and 1.23 (95% CI: 1.09–1.38) for C6, respectively. The fully adjusted SHRs for cardiovascular mortality were 1.11 (95% CI: 1.01–1.21) for C4, 1.19 (95% CI: 1.05–1.34) for C5, and 1.36 (95% CI: 1.09–1.70) for C6. In the age-stratification, an increased risk of hypotension was observed with older age. The HR for C1 was 1.28 (95% CI: 1.16–1.41) for ≥85 years. Conclusions: Hypertension increased the risk of all-cause and cardiovascular mortality among those aged 65–74 and 75–84 years, but not among those aged ≥85 years. Geriatr Gerontol Int 2024; ••: ••–••. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 1432-1076 184 1 2024 In vitro fertilization and long-term child health and development: nationwide birth cohort study in Japan 24 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Mitsui Department of Obstetrics and Gynecology, Okayama University Graduate School of Medicine Tomoka Kadowaki Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Tomoya Hirota Department of Psychiatry and Behavioral Sciences, UCSF Weill Institute for Neurosciences, University of California San Francisco Hisashi Masuyama Department of Obstetrics and Gynecology, Okayama University Graduate School of Medicine Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University The aim of this study is to compare long-term health outcomes between IVF-conceived children and non-IVF-conceived children in Japan, in the context of strong recommendation for single embryo transfer. Using data from a nationwide birth cohort linked with perinatal database, this study analyzed 2140 children born in Japan in May 2010. It compared child health and development outcomes up to 9 years of age between IVF-conceived and non-IVF-conceived children (binary exposure). A Poisson regression with robust variance to estimate the risk ratios for the association between IVF and various long-term child health and developmental outcomes. After adjusting for confounding factors, no significant differences were observed between IVF-conceived and naturally conceived children for most outcomes, including hospitalization, obesity, and developmental milestones. IVF-conceived children showed a slightly lower risk of attention problems at 8 years (adjusted Risk Ratio [aRR]: 0.73, 95% CI: 0.53–1.00). In subgroup analyses, IVF-conceived term children and singletons demonstrated reduced risk of cognitive delays at 5.5 years (aRR: 0.31, 95% CI: 0.10–0.96 and aRR: 0.37, 95% CI: 0.14–0.98, respectively). Conclusion: In this Japanese cohort, IVF conception was not associated with adverse long-term health or developmental outcomes. These findings provide reassurance about the safety of IVF, particularly in the context of single embryo transfer policies. Further research is needed to explore specific IVF protocols and subgroups. No potential conflict of interest relevant to this article was reported.

Japan Medical Association Acta Medica Okayama 2433-3298 6 4 2023 Effectiveness of the Original COVID-19 Vaccine against COVID-19 Exacerbations during the Omicron Wave: A Population-based Study in Okayama, Japan 463 469 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Rumi Matsuo Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Introduction: In Japan, approximately 97 million individuals have received their primary two doses of coronavirus disease 2019 (COVID-19) vaccine at the end of 2022. In this study, we aim to examine the effectiveness of the primary vaccines and compare its efficacy to booster vaccine shots in terms of preventing COVID-19 exacerbations during the Omicron-predominant period in Japan. Methods: For this analysis, we have collected all the confirmed COVID-19-positive cases from different medical institutions in Okayama City and have also utilized the information from the public Vaccination Record System. Taking the number of vaccinations into consideration, we then conducted a population-based study to assess the effectiveness of the two primary vaccine doses in preventing COVID-19 exacerbations during the Omicron waves. Our primary and secondary outcomes were COVID-19 exacerbations with respiratory failure (i.e., oxygen saturation on room air ≤ 93%, requiring supplemental oxygen), intensive care unit admission and/or mechanical ventilator requirement, or death, in accordance with the Japanese COVID-19 guidelines, and pneumonia during the course of COVID-19 infection, respectively. Results: In total, 95,329 COVID-19-positive individuals, aged 5 years and above, were included in this analysis (study period from January 1 to September 10, 2022). As per our findings, the effectiveness of the primary two doses against COVID-19 exacerbations compared with those who had never been vaccinated was 55.5% (95% confidential interval [CI]: 32.6-71.7), whereas it was higher after the third dose (76.9%; 95% CI: 66.7-84.0) and the fourth dose (75.7%; 95% CI: 58.8-85.7). Effectiveness was sustained for ≥ 5 months after the third vaccination, and preventive effectiveness was observed in individuals aged ≥ 65 years. Conclusions: As per the results of this study, we can conclude that the efficacy of the primary two doses of SARS-CoV-2 vaccine can be further strengthened in terms of preventing COVID-19 exacerbations by administering third and fourth booster vaccine shots. The additional bivalent vaccine is anticipated to further increase its efficacy against the Omicron strain, suggesting that individuals who have not received their booster shots yet should consider getting them to prevent COVID-19 exacerbations. No potential conflict of interest relevant to this article was reported.

Nature Portfolio Acta Medica Okayama 2045-2322 14 1 2024 A nationwide longitudinal survey of infantile injury and its recurrence in Japan 24716 EN Tomohiro Hiraoka Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Takafumi Obara Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Kohei Tsukahara Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Takashi Hongo Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Tsuyoshi Nojima Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Masaki Hisamura Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Tetsuya Yumoto Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Atsunori Nakao Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Hiromichi Naito Department of Emergency, Critical Care, and Disaster Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences Injury recurrence in young children is a significant public health concern, as it may indicate an unfavorable home environment. This study evaluates whether infantile injuries increase recurrence during preschool years, contributing to more effective prevention strategies for vulnerable families. The study included 20,191 children from "The Longitudinal Survey of Babies in the 21st Century," a representative sample of infants born in Japan between May 10 and 24, 2010. We conducted a logistic regression analysis to compare injury recurrence risk between children aged 18 months to seven years with and without infantile injury histories. The study revealed that infants with a history of injuries had a higher risk of subsequent hospital visits for injuries during preschool years (crude Odds Ratio (cOR) 1.52, 95% CI, 1.41-1.64, adjusted OR (aOR) 1.48, 95% CI 1.37-1.60). Specific injuries, such as falls (aOR 1.34, 95% CI, 1.26-1.43), pinches (aOR 1.22, 95% CI, 1.15-1.29), drowning (aOR 1.29, 95% CI, 1.19-1.40), ingestion (aOR 1.35, 95% CI, 1.17-1.55), and burns (aOR 1.47, 95% CI, 1.31-1.65), independently increased the risk of future injuries. Our findings highlight the necessity of universal safety measures in the home environment and targeted interventions for families with a history of high-risk injuries. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 78 5 2024 Small-for-Gestational-Age Status and the Risk of Kawasaki Disease: A Nationwide Birth Cohort in Japan 363 370 EN Satoe Takanaga Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Original Article 10.18926/AMO/67656 Kawasaki disease (KD) is a pediatric disease of unknown etiology that commonly affects infants in East Asia. Infants born small for gestational age (SGA) have weaker immune systems and are more susceptible to infection. Using data from a nationwide Japanese birth cohort study conducted in 2010 (n=34,579), we investigated whether SGA increases the risk of KD. SGA was defined as birth weight below the 10th percentile for gestational age. The outcome was hospitalization for KD between 6 and 30 months of age. The association between SGA and hospitalization for KD, adjusted for child and maternal factors, was examined using logistic regression. Of the 231 children hospitalized for KD, 9.5% were SGA. Further statistical analysis showed that SGA did not increase the odds ratio (OR) of hospitalization for KD (adjusted OR 1.12, 95% confidence interval 0.71-1.75). This result was not changed with stratification by early daycare attendance and preterm status. Reasons for the lack of association may include the multifactorial pathogenesis of KD; in addition, the types of infections to which SGA infants are predisposed may differ from those triggering KD. Overall, our large nationwide study found no association between SGA and KD. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 0264-410X 42 21 2024 Kinetics of SARS-CoV-2 antibody titers after booster vaccinations during an Omicron surge in Japan 126156 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Ayako Sasaki Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Background: Despite the emergence of SARS-CoV-2 variants and waning immunity after initial vaccination, data on antibody kinetics following booster doses, particularly those adapted to Omicron subvariants like XBB.1.5, remain limited. This study assesses the kinetics of anti-spike protein receptor-binding domain (S-RBD) IgG antibody titers post-booster vaccination in a Japanese population during the Omicron variant epidemic. Methods: A prospective cohort study was conducted in Bizen City, Japan, from November 2023 to January 2024. Participants included residents and workers aged ≥18 years, with at least three COVID-19 vaccinations. Antibody levels were measured from venous blood samples. The study analyzed 424 participants and 821 antibody measurements, adjusting for variables such as age, sex, underlying conditions, and prior infection status. Mixed-effects models were employed to describe the kinetics of log-transformed S-RBD antibody titers. Results: The study found that S-RBD antibody titers declined over time but increased with the number of booster vaccinations, particularly those adapted to Omicron and its subvariant XBB.1.5 (Pfizer-BioNTech Omicron-compatible: 0.156, 95%CI －0.032 to 0.344; Pfizer-BioNTech XBB-compatible: 0.226; 95%CI －0.051 to 0.504; Moderna Omicron-compatible: 0.279, 95%CI 0.012 to 0.546; and Moderna XBB-compatible: 0.338, 95%CI －0.052 to 0.728). Previously infected individuals maintained higher antibody titers, which declined more gradually compared to uninfected individuals (coefficient for interaction with time 0.006; 95%CI 0.001 to 0.011). Sensitivity analyses using Generalized Estimating Equations and interval-censored random intercept model confirmed the robustness of these findings. Conclusions: The study provides specific data on antibody kinetics post-booster vaccination, including the XBB.1.5-adapted vaccine, in a highly vaccinated Japanese population. The results highlight the importance of considering individual demographics and prior infection history in optimizing vaccination strategies. No potential conflict of interest relevant to this article was reported.

Nature Portfolio Acta Medica Okayama 2045-2322 14 1 2024 Longitudinal antibody dynamics after COVID-19 vaccine boosters based on prior infection status and booster doses 4564 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Ayako Sasaki Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Global concern over COVID-19 vaccine distribution disparities highlights the need for strategic booster shots. We explored longitudinal antibody responses post-booster during the Omicron wave in a Japanese cohort, emphasizing prior infection and booster doses. This prospective cohort study included 1763 participants aged 18 years and older with at least three vaccine doses (7376 datapoints). Antibody levels were measured every 2 months. We modeled temporal declines in antibody levels after COVID-19 vaccine boosters according to prior infection status and booster doses using a Bayesian linear mixed-effects interval-censored model, considering age, sex, underlying conditions, and lifestyle. Prior infection enhanced post-booster immunity (posterior median 0.346, 95% credible interval [CrI] 0.335-0.355), maintaining antibody levels (posterior median 0.021; 95% CrI 0.019-0.023) over 1 year, in contrast to uninfected individuals whose levels had waned by 8 months post-vaccination. Each additional booster was correlated with higher baseline antibody levels and slower declines, comparing after the third dose. Female sex, older age, immunosuppressive status, and smoking history were associated with lower baseline post-vaccination antibodies, but not associated with decline rates except for older age in the main model. Prior infection status and tailored, efficient, personalized booster strategies are crucial, considering sex, age, health conditions, and lifestyle. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 2189-7948 25 2 2024 Treatment interruption in hypertensive patients during the COVID-19 pandemic: An interrupted time series analysis using prescription data in Okayama, Japan 102 109 EN Naoko Nakamura Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shunsaku Hayase Academic Affairs Division, Okayama University Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Background: The COVID- 19 pandemic has impacted healthcare behaviors, leading to fewer pediatric visits in Japan and potentially fewer visits by adult patients. However, existing Japanese studies on treatment interruptions have generally relied on questionnaire- based methods. In this study, we assessed the impact of the pandemic on antihypertensive treatment interruption using real- world prescription data. Methods: We conducted an interrupted time series analysis using the National Health Insurance Database in Okayama Prefecture, Japan. Participants included individuals aged 40-69 years with at least one antihypertensive prescription between 2018 and 2020. Treatment interruption was defined as a 3- month or longer gap in prescriptions after medication depletion. We used segmented Poisson regression with models unadjusted and adjusted for seasonality and over- dispersion to assess monthly treatment interruptions before and after Japan's April 2020 emergency. Results: During the study period, 23.0% of 55,431 participants experienced treatment interruptions. Cyclical fluctuations in interruptions were observed. The crude analysis indicated a 1.2 - fold increase in treatment interruptions following the pandemic; however, the adjusted models showed no significant changes. Even among higher- risk groups, such as women, younger adults, and those with shorter prescriptions, no significant alterations were observed. Conclusion: We found no significant impact of the COVID- 19 pandemic on antihypertensive treatment interruption in Okayama Prefecture. The less severe outbreak in the area or increased use of telemedicine and extended prescriptions may have contributed to treatment continuity. Further research is needed using a more stable and comprehensive database, broader regional data, and detailed prescription records to validate and extend our findings. No potential conflict of interest relevant to this article was reported.

岡山医学会 Acta Medica Okayama 0030-1558 135 3 2023 令和４年度岡山医学会賞　総合研究奨励賞（結城賞） 106 108 EN Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 6 2023 Review of a Series of Surveys on Adverse Reactions to the COVID-19 mRNA-1273 Vaccine at Okayama University 567 575 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Chigusa Higuchi Okayama University Health Service Center Chikara Miyaji Okayama University Health Service Center Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Hideharu Hagiya Department of Infectious Diseases, Okayama University Hospital Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Review 10.18926/AMO/66148 This paper presents the results of a series of surveys conducted from July 2021 to March 2023 to investigate the post-vaccination adverse reactions to the mRNA-1273 (Moderna) vaccine among faculty, staff, and students at Okayama University. These studies complement the official surveys conducted by the Ministry of Health, Labour and Welfare (MHLW) and provide a more representative picture of adverse reactions in the general population including large numbers of healthy young people. Pain, swelling, redness at the injection site, fever, headache, and malaise were the main adverse reactions reported. The proportion of adverse reactions was generally higher after the second vaccination and decreased with each additional vaccination. No statistically significant differences in the adverse reactions were found for males and females and those with/without a history of allergy, but a lower proportion of fever was observed in older participants and those with underlying medical conditions. We also evaluated the association between adverse reactions and antibody titers after the third vaccination and found no significant differences in antibody levels one month after vaccination. This series of studies highlights the importance of conducting surveys in diverse populations to provide a more representative picture of post-vaccination adverse reactions during a pandemic. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 1328-8067 65 1 2023 Adverse reactions in young children receiving the coronavirus disease 2019 vaccine e15696 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Junya Shimizu Department of Pediatrics, National Hospital Organization, Okayama Medical Center Yuji Yokoyama Department of Pediatrics, Okayama Aiiku Clinic Hirokazu Tsukahara Department of Pediatrics, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Background: We sought to investigate the occurrence of adverse reactions in Japanese children aged 6 months to 4 years who received the BNT162b2 coronavirus disease 2019 (COVID-19) vaccine, to examine parental considerations, and to evaluate potential risk factors associated with post-vaccination fever. Methods: This cross-sectional survey study targeted 1617 children aged 6 months to 4 years who received their primary doses of BNT162b2 from November 10, 2022, to April 30, 2023, in Okayama Prefecture. We surveyed the occurrence of local and systemic reactions within 1 week after vaccination, and described the incidence proportions of adverse reactions for 515 participants overall and by age group. The study also examined the impact of previous COVID-19 infection and co-administration of the seasonal influenza vaccine on post-vaccination fever. A survey also assessed parents' reasons for vaccinating their children and the sources of information they used. Results: Adverse reactions were infrequent (5.2%, with fever ≥37.5°C; no cases exceeded 39°C) and did not increase with vaccine doses administered. The risk of post-vaccination fever was not statistically associated with a history of COVID-19―the adjusted risk ratio (aRR) was 0.99, and the 95% confidence interval (CI) was 0.41–2.39―but was associated with co-administration of the seasonal influenza vaccine (aRR 3.24, 95% CI 1.14–9.18). Parental decisions regarding vaccination were influenced by official government guidelines and primary care physicians' opinion. Conclusion: This study provides valuable insight into the safety profile of the BNT162b2 vaccine in Japanese children aged 6 months to 4 years. Further research involving larger cohorts and appropriate control groups is needed. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1661-6596 24 20 2023 Roles of Oxidative Injury and Nitric Oxide System Derangements in Kawasaki Disease Pathogenesis: A Systematic Review 15450 EN Mitsuru Tsuge Department of Pediatrics, Okayama University Academic Field of Medicine, Dentistry, and Pharmaceutical Sciences Kazuhiro Uda Department of Pediatrics, Okayama University Academic Field of Medicine, Dentistry, and Pharmaceutical Sciences Takahiro Eitoku Department of Pediatrics, Kawasaki Medical School Naomi Matsumoto Department of Epidemiology, Okayama University Academic Field of Medicine, Dentistry, and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Okayama University Academic Field of Medicine, Dentistry, and Pharmaceutical Sciences Hirokazu Tsukahara Department of Pediatrics, Okayama University Academic Field of Medicine, Dentistry, and Pharmaceutical Sciences Kawasaki disease (KD) is an acute febrile vasculitis that occurs mostly in children younger than five years. KD involves multiple intricately connected inflammatory reactions activated by a cytokine cascade. Despite therapeutic advances, coronary artery damage may develop in some patients, who will be at risk of clinical cardiovascular events and even sudden death. The etiology of KD remains unclear; however, it may involve both genetic and environmental factors leading to aberrant inflammatory responses. Given the young age of onset, prenatal or perinatal exposure may be etiologically relevant. Multisystem inflammatory syndrome in children, a post-infectious hyper-inflammatory disorder associated with severe acute respiratory syndrome coronavirus 2, has features that overlap with those of KD. Available evidence indicates that vascular endothelial dysfunction is a critical step in the sequence of events leading to the development of cardiovascular lesions in KD. Oxidative stress and the dysregulation of the nitric oxide (NO) system contribute to the pathogenesis of inflammatory responses related to this disease. This review provides current evidence and concepts highlighting the adverse effects of oxidative injury and NO system derangements on the initiation and progression of KD and potential therapeutic strategies for cardiovascular pathologies in affected children. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 5 2023 Participation in the Setouchi Triennale and the Health of Residents in Naoshima: A Cross-Sectional Study 491 497 EN Hiroshi Habu Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Chikara Miyaji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Ken Aoo Graduate School of Humanities and Social Sciences, Okayama University Yosuke Nishita Graduate School of Humanities and Social Sciences, Okayama University Masao Tsuri Faculty of Economics, Musashi University Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Original Article 10.18926/AMO/65971 Arts festivals have become increasingly popular in various parts of Japan in recent years. The purpose of this study was to investigate the relationships between arts festival activities participation at the Setouchi Triennale and the health of residents in the town of Naoshima. This was a cross-sectional study. Questionnaires were distributed to all residents of Naoshima who were 20 years old or older (n=2,588). We analyzed responses from 708 people. The associations between arts festival activities participation and health (measured by self-rated health) were analyzed using logistic regression analysis as the primary outcome. Kessler’s psychological distress scale scores were also analyzed in the same manner as the primary outcome. The participating group had an adjusted odds ratio of 1.86 (95% confidence interval: 1.03-3.33) for higher self-rated health compared with those who did not participate. Kessler’s psychological distress scale results showed that the participating group had an adjusted odds ratio of 3.23 (95% confidence interval: 1.19-8.81) for lower psychological distress compared with those who did not participate. In conclusion, arts festival activities participation was associated with higher self-rated health and lower psychological distress. However, caution must be taken in regard to generalizability and causality when interpreting these results. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 5 2023 Childcare and Child Development in Japan 479 490 EN Akiko Murata Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Chikara Miyaji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Original Article 10.18926/AMO/65970 For decades, the notion has persisted in developed countries that exclusive care by the mothers is best for the development of children up to 3 years of age. To examine the veracity of this “myth of the first three years” in Japan, we examined the effects of childcare facility use for children younger than 3 years on their development using the cohorts of the Longitudinal Survey of Newborns in the 21st Century conducted in Japan. Of the 47,015 respondents to the survey, we studied the children of 5,508 mothers with university/professional education to evaluate the relationships between primary early (< 2.5 years) childcare providers during weekday daytime hours and specific development indices for the ages of 2.5, 5.5, and 8 years. At the age of 2.5 and 5.5 years, children attending childcare facilities were judged as having more advanced developmental behaviors by their parents, such as being able to compose a two-word sentence (adjusted odds ratio [aOR]: 0.22) or to express emotions (aOR: 0.81), compared with those cared for by mothers. However, at the age of 8 years, children who attended childcare facilities as infants < 2.5 years showed more aggressive behavior in interrupting people (aOR: 1.20) and causing disturbances in public (aOR: 1.26) than those cared for by mothers (after adjustment for numerous child and parental factors). Although these results are generally consistent with previous studies, issues potentially involved with problem behavior such as quality of childcare require further investigation, as does the case of children of mothers with more modest educational attainment. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 5 2023 Does Participation in the Setouchi Triennale Foster Social Capital? : A Cross-Sectional Study 443 449 EN Chikara Miyaji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroshi Habu Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Ken Aoo Graduate School of Humanities and Social Sciences, Okayama University Yosuke Nishita Graduate School of Humanities and Social Sciences, Okayama University Masao Tsuri Faculty of Economics, Musashi University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Original Article 10.18926/AMO/65966 This study examined whether participation in an art project was associated with higher social capital (SC). We conducted a questionnaire survey from November 2021 to March 2022 among residents aged 20 years or older of Naoshima, an island in Kagawa Prefecture, Japan. Before the survey, the Setouchi Triennale had been held on Naoshima four times, starting in 2010. We calculated propensity scores for Triennale participation and performed propensity score matching. We then compared cognitive and structural SC by Triennale participation and found significant differences, respectively. We adopted a conditional ordered logistic regression analysis with propensity score matching for cognitive or structural SC, and found adjusted odd ratios of 2.913 (95%CI, 1.846-4.596) for cognitive SC and 4.535 (95%CI, 2.839-7.244) for structural SC. Our findings suggest that Triennale participation enhanced the cognitive aspect of SC while also building structural SC. No potential conflict of interest relevant to this article was reported.

Japan Epidemiological Association Acta Medica Okayama 0917-5040 32 12 2022 Association Between Fever and Antibody Titer Trends After a Third Dose of the mRNA-1273 Vaccine 567 569 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Rumi Matsuo Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Ayako Sasaki Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Chikara Miyaji Okayama University Health Service Center Chigusa Higuchi Okayama University Health Service Center Masanori Nakayama Office of Innovative Medicine, Organization for Research Strategy and Development, Okayama University Yasue Sakurada Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Hideharu Hagiya Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Fumio Otsuka Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University No potential conflict of interest relevant to this article was reported.

Japan Epidemiological Association Acta Medica Okayama 0917-5040 33 2 2023 Adverse Reactions and Attitudes Toward the BNT162b2 COVID-19 Vaccine in Children 5 to 11 Years of Age in Japan 110 111 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Junya Shimizu Department of Pediatrics, National Hospital Organization, Okayama Medical Center Yuji Yokoyama Department of Pediatrics, Okayama Aiiku Clinic Hirokazu Tsukahara Department of Pediatrics, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University No potential conflict of interest relevant to this article was reported.

BMC Acta Medica Okayama 1471-2458 23 1 2023 Longitudinal impact of the COVID-19 pandemic on the development of mental disorders in preadolescents and adolescents 1308 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Dentistry, and Phar�maceutical Sciences, Okayama University Graduate School of Medicine Satoe Takanaga Department of Epidemiology, Dentistry, and Phar�maceutical Sciences, Okayama University Graduate School of Medicine Yoshie Shigeyasu Department of Pediatrics, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Ayumi Okada Department of Pediatrics, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Background　School closures and social distancing may have affected mental health among preadolescent and adolescent children, who are in a social developmental stage. Rates of anxiety, depression, and stress have been reported to have increased during the COVID-19 pandemic among teenagers worldwide. However, most studies have measured children's mental health in cross-sectional studies or short-term comparisons before and after lockdowns and school closures, and few studies have tracked the long-term effects on mental health among children and adolescents, despite the pandemic lasting more than 2 years. Methods　An interrupted time-series analysis was performed for longitudinal changes in the monthly number of new mental disorders (eating disorders, schizophrenia, mood disorders, and somatoform disorders). Using a nationwide multicenter electronic health records database in Japan, we analyzed data of patients aged 9 to 18 years from 45 facilities that provided complete data throughout the study period. The study period covered January 2017 to May 2021, defining a national school closure as an intervention event. We modeled the monthly new diagnoses of each mental disorder using a segmented Poisson regression model. Results　The number of new diagnoses throughout the study period was 362 for eating disorders, 1104 for schizophrenia, 926 for mood disorders, and 1836 for somatoform disorders. The slope of the regression line in monthly number of new diagnoses increased in the post-pandemic period for all targeted mental disorders (change in slope for eating disorders 1.05, 95% confidence interval [CI] 1.00-1.11; schizophrenia 1.04, 95% CI 1.01-1.07; mood disorders 1.04, 95% CI 1.01-1.07; and somatoform disorders 1.04 95% CI 1.02-1.07). The number of new diagnoses for schizophrenia and mood disorders increased early after school closure; while eating disorders showed an increasing trend several months later. Somatoform disorders showed a decreasing trend followed by an increasing trend. Time trends by sex and age also differed for each mental disorder. Conclusions　In the post-pandemic period, the number of new cases increased over time for eating disorders, schizophrenia, mood disorders, and somatoform disorders. The timing of increase and trends by sex and age differed for each mental disorder. No potential conflict of interest relevant to this article was reported.

Fuji Technology Press Ltd. Acta Medica Okayama 1883-8030 17 1 2022 Questionnaire Survey on COVID-19 Vaccination at Okayama University in Japan: Factors Promoting Vaccination Among Young Adults 21 30 EN Chigusa Higuchi Okayama University Health Service Center Naomi Matsumoto Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Yoshiaki Iwasaki Okayama University Health Service Center Takashi Yorifuji Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Junichiro Yamazaki Okayama University Yasutomo Nasu Okayama University Hirofumi Makino Okayama University COVID-19 has been prevalent worldwide since 2019. Increasing COVID-19 vaccination coverage is an important measure to combat the disease. An online survey was conducted with university students and personnel who were vaccinated against COVID-19 at a mass vaccination event to examine the factors promoting vaccination among young adults. The online survey was conducted with persons vaccinated at Okayama University from June 5 to September 27, 2021. Although the number of those who had fever >37.5°C increased after the second vaccination compared to the first, the vaccinated persons got more satisfied after the second shot. No potential conflict of interest relevant to this article was reported.

nature portfolio Acta Medica Okayama 2045-2322 12 1 2022 Early-stage antibody kinetics after the third dose of BNT162b2 mRNA COVID-19 vaccination measured by a point-of-care fingertip whole blood testing 20628 EN Hideharu Hagiya Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yasuhiro Nakano Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masanori Furukawa Clinical Laboratory, Okayama University Hospital Naruhiko Sunada Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toru Hasegawa Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yasue Sakurada Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kou Hasegawa Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Koichiro Yamamoto Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroko Ogawa Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takafumi Obara Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kouhei Ageta Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Rumi Matsuo Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tomoka Kadowaki Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Akihito Higashikage Clinical Laboratory, Okayama University Hospital Takao Hikita Office of Innovative Medicine, Organization for Research Strategy and Development, Okayama University Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shinichi Toyooka Departments of General Thoracic Surgery and Breast and Endocrinological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshinobu Maeda Department of Hematology and Oncology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshinori Yokokura Yokokura Hospital Fumio Otsuka Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masanori Nakayama Office of Innovative Medicine, Organization for Research Strategy and Development, Okayama University Amid the Coronavirus Disease 2019 pandemic, we aimed to demonstrate the accuracy of the fingertip whole blood sampling test (FWT) in measuring the antibody titer and uncovering its dynamics shortly after booster vaccination. Mokobio SARS-CoV-2 IgM & IgG Quantum Dot immunoassay (Mokobio Biotechnology R&D Center Inc., MD, USA) was used as a point-of-care FWT in 226 health care workers (HCWs) who had received two doses of the BNT162b2 mRNA vaccine (Pfizer-BioNTech) at least 8 months prior. Each participant tested their antibody titers before and after the third-dose booster up to 14-days. The effect of the booster was observed as early as the fourth day after vaccination, which exceeded the detection limit (>30,000 U/mL) by 2.3% on the fifth day, 12.2% on the sixth day, and 22.5% after the seventh day. Significant positive correlations were observed between the pre- and post-vaccination (the seventh and eighth days) antibody titers (correlation coefficient, 0.405; p<0.001). FWT is useful for examining antibody titers as a point-of-care test. Rapid response of antibody titer started as early as the fourth day post-vaccination, while the presence of weak responders to BNT162b2 vaccine was indicated. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 2213-2198 10 12 2022 Impact of COVID-19 pandemic-associated reduction in respiratory viral infections on childhood asthma onset in Japan 3306 3308.e2 EN Naomi Matsumoto Department of Epidemiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University Tomoka Kadowaki Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Satoe Takanaga Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Masanori Ikeda Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 2296-2360 11 2023 Evaluation of the association of birth order and group childcare attendance with Kawasaki disease using data from a nationwide longitudinal survey 1127053 EN Takahiro Namba Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Akihito Takeuchi Department of Neonatology, National Hospital Organization Okayama Medical Center Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Mitsuru Tsuge Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masato Yashiro Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hirokazu Tsukahara Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Background: Kawasaki disease (KD) is a form of pediatric systemic vasculitis. Although the etiology remains unclear, infections have been identified as possible triggers. Children with a later birth order and those who attend childcare are at a higher risk of infections due to exposure to pathogens from their older siblings and other childcare attendees. However, longitudinal studies exploring these associations are limited. Thus, we aimed to elucidate the relationship between birth order, group childcare attendance, and KD, using a nationwide longitudinal survey in Japan. Methods: In total, 36,885 children born in Japan in 2010 were included. The survey used questionnaires to identify hospitalized cases of KD. We evaluated the relationship between birth order classification, group childcare attendance, and KD prevalence every year, from 6 to 66 months of age. For each outcome, odds ratios (ORs), and 95% confidence intervals (CIs) were estimated after adjusting for child factors, parental factors, and region of residence. Results: Children with higher birth orders were more likely to be hospitalized with KD at 6-18 months of age (second child OR: 1.77, 95% CI: 1.25-2.51; third child OR: 1.70, 95% CI: 1.08-2.65). This trend was stronger for children who did not attend group childcare (second child OR: 2.51, 95% CI: 1.57-4.01; third child OR: 2.41, 95% CI: 1.30-4.43). An increased risk of KD hospitalization owing to the birth order was not observed in any age group for children in the childcare group. Conclusions: Children with higher birth orders were at high risk for hospitalization due to KD at 6-18 months of age. The effect of birth order was more prominent among the children who did not attend group childcare. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 2023 Cultural Activities and Health; Fostering Social Capital EN Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroshi Habu Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Chikara Miyaji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 2023 文化活動と健康の関連；ソーシャル・キャピタルの醸成 EN Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Chikara Miyaji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences No potential conflict of interest relevant to this article was reported.

岡山医学会 Acta Medica Okayama 0030-1558 134 1 2022 新型コロナウイルスワクチン副反応調査の報告 35 42 EN Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Chigusa Higuchi Health Service Center, Okayama University Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Hideharu Hagiya Department of General Medicine; Setouchi (Marugame) Division, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Soshi Takao Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 1341-321X 29 1 2022 Examining the association between vaccine reactogenicity and antibody titer dynamics after the third dose of BNT162b2 vaccine using a mixed-effects model 39 42 EN Naomi Matsumoto Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Hideharu Hagiya Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masanori Nakayama Office of Innovative Medicine, Organization for Research Strategy and Development, Okayama University Masanori Furukawa Clinical Laboratory, Okayama University Hospital Toshiharu Mitsuhashi Center for Innovative Clinical Medicine, Okayama University Hospital Soshi Takao Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Fumio Otsuka Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Takashi Yorifuji Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Background: To mitigate the COVID-19 pandemic, many countries have recommended the use of booster vac-cinations. The relationship between the degree of adverse vaccine reactions and elevated antibody titers is of interest; however, no studies have investigated the temporal changes in antibody titers based on repeated measurements after a third dose of the BNT162b2 vaccine. Methods: This prospective longitudinal cohort study was conducted with 62 healthcare workers who received a third dose of the BNT162b2 at Okayama University Hospital, Japan. Venous blood draw and fingertip whole blood test sample collection were conducted at the early (3-13 days) and 1-month time points; only FWT sample collection was conducted at the 2-month time point. Information on adverse reactions within 1 week after vaccination was also obtained. The association between fever of 37.5 degrees C or higher and antibody titers after the third dose of BNT162b2 was examined using a mixed-effects model and Poisson regression with robust variance. Results: A trend toward higher antibody titers in the early period after vaccination was observed in the febrile individuals, but the differences were not significant at 1 and 2 months post-vaccination (the partial regression coefficient for fever was 8094.3 [-1910.2, 18,098.8] at 1 month after vaccination, and 1764.1 [-4133.9, 7662.1] at 2 months after vaccination in the adjusted models). Conclusion: The findings suggest that the presence of fever after the third vaccine does not predict a sustained elevation in serum antibody titers. No potential conflict of interest relevant to this article was reported.