ImportanceAlthough a growing number of studies have reported negative associations of the COVID-19 pandemic with academic performance among school-aged children, less is known about the pandemic’s association with early childhood development.ObjectiveTo examine the association between the COVID-19 pandemic and early childhood development.Design, Setting, and ParticipantsIn this cohort study conducted in all accredited nursery centers in a Japanese municipality, baseline surveys of children aged 1 and 3 years (1000 and 922, respectively) were conducted between 2017 and 2019, and participants were followed up for 2 years.ExposureChildren’s development was compared at age 3 or 5 years between cohorts that were exposed to the pandemic during the follow-up and a cohort that was not.Main Outcome and MeasureChildren’s developmental age was measured by nursery teachers using the Kinder Infant Development Scale (KIDS). Data were analyzed between December 8, 2022, and May 6, 2023.ResultsA total of 447 children (201 girls [45.0%] and 246 boys [55.0%]) aged 1 year at baseline were followed up to age 3 years, and 440 children (200 girls [45.5%] and 240 boys [54.5%]) aged 3 years at baseline were followed up to age 5 years. During the follow-up, the cohorts that were exposed to the pandemic were 4.39 months behind in development at age 5 compared with the cohort that was not (coefficient, −4.39; 95% credible interval, −7.66 to −1.27). Such a negative association was not observed in development at age 3 years (coefficient, 1.32; 95% credible interval, −0.44 to 3.01). Variations in development were greater during the pandemic than before the pandemic regardless of age. Additionally, the quality of care at nursery centers was positively associated with development at age 3 years during the pandemic (coefficient, 2.01; 95% credible interval, 0.58-3.44), while parental depression appeared to amplify the association between the pandemic and delayed development at age 5 (coefficient of interaction, −2.62; 95% credible interval, −4.80 to −0.49; P = .009).Conclusions and RelevanceThe findings of this study showed an association between exposure to the pandemic and delayed childhood development at age 5 years. Variations in development widened during the pandemic regardless of age. It is important to identify children with developmental delays associated with the pandemic and provide them with support for learning, socialization, physical and mental health, and family support.

This study presents the first quantitative evaluation of the quality of early childhood education and care (ECEC) in Japan to make a significant contribution to the body of knowledge accumulated on ECEC in countries where research has been limited. We observed 30 classes comprising 3-year-olds, 28 classes comprising 5-year-olds, and 30 classes comprising mixed-ages from publicly provided nursery centers under the jurisdiction of the Kanto metropolitan area, Japan. An internationally-recognized quality rating scale for ECEC called the Early Childhood Environment Rating Scale, 3rd edition, which consists of six subscales, was used for this study. In contrast to previous studies conducted in the US, the results of this study showed that the Japanese ECEC is characterized as showing higher scores in the two subscales, “Personal Care Routines” and “Interaction,” and showing lower score in the subscale, “Learning Activities.” In addition, this study showed that the quality of ECEC varied across nursery centers. Furthermore, with regard to the two subscales, “Interaction” and “Language and Literacy,” the degree of variation within centers differed across nursery centers. This study analyzed how these characteristics of Japanese ECEC can be partly produced by the existence of national guideline for nursery centers authorized by the Japanese government. In addition, mechanisms producing differences in the quality of ECEC among and within centers were also discussed.

Background Public health depends on both medical treatment development and the public’s willingness to take such treatment. To determine whether having experienced delayed localized hypersensitivity reactions to COVID-19 vaccines, i.e., “COVID arm” symptoms affect confidence in the safety of vaccination, willingness to take COVID-19 vaccines, and the acknowledgement of the importance of vaccination, and also confidence in science. Methods We implemented a panel survey on internet in February 2021 and March 2022 in Japan, before and after COVID-19 vaccines were administered to the public in Japan, and we used “COVID arm” symptoms, which are independent of one’s prior confidence in vaccination, as our instrument. Out of the non-probability sample of 15,000 respondents in the first wave in February 2021, 9,668 responded to the second wave conducted in March 2022. We used “COVID arm” symptoms as a natural experiment conditional on the background characteristics of the respondents. Main outcomes are whether having experienced “COVID arm” symptoms affected 1) confidence in the safety of vaccination; 2) willingness to take the next dose of COVID-19 vaccines, 3) acknowledgment of the importance of vaccination, and 4) confidence in science. Measures are marginal means of the probability of a positive reaction to each question. Results Experiencing “COVID arm” symptoms significantly lowered confidence in the safety of vaccination by 3.4 percentage points and the probability of taking a second and third dose of COVID-19 vaccine by 1.2 and 3.4 percentage points, respectively. Adverse impacts were observed regardless of prior confidence in vaccination. Experiencing such symptoms affected neither the acknowledged importance of vaccination nor confidence in science. Conclusions Updates to beliefs about side effects affected confidence in the safety of vaccination. Acknowledgment of vaccination importance and general confidence in science are likely to have factored in the uncertainty and to be tolerant of updates to one’s beliefs about side effects. Belief updates of specific treatments had asymmetric impacts on the treatment and medicine in general. Trial registration The design of the survey was preregistered with the American Economic Association’s RCT Registry [1].

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