本田 仁

Few longitudinal studies have examined the impact of the COVID-19 pandemic on personal behaviors. This study investigated changes in four social behaviors among the Japanese public during and after the COVID-19 pandemic, using four-wave longitudinal data (2020-2023) from the Japan COVID-19 and Society Internet Survey (JACSIS). In total, 8622 respondents continuously participated in the surveys. In JACSIS 2023, the percentage of individuals who always refrained from specific actions decreased compared with 2020: traveling (71.0%-30.9%), non-essential and non-urgent outings (60.6%-24.5%), crowded spaces (62.6%-28.0%), and eating out (49.5%-21.6%). Mixed-effects logistic regression analysis indicated that essential health care workers displayed more cautious behavior than other workers, and respondents were less likely to refrain from these actions in JACSIS 2023 compared with 2020. Understanding behavioral changes is crucial to evaluating the efficacy of COVID-19 prevention measures and improving future pandemic response strategies.

Background/Objectives: Japan's COVID-19 vaccination campaign achieved high coverage by 2022, yet limited national-level data has hindered evaluations of vaccine effectiveness. This study analyzed the impact of vaccines on infection outcomes while considering socioeconomic and behavioral factors in the Japanese population. Methods: A total of 19,482 individuals aged 16-81 years, who participated in both the 2021 (baseline) and 2022 (follow-up) waves of an Internet-based survey, were analyzed. Vaccine intake during the follow-up period (0/1/2+ doses) served as the exposure, while outcomes included COVID-19 diagnosis, hospitalization, and receipt of oxygenation/ventilation. Adjusted prevalence ratios (APRs) were calculated using Poisson regression models, controlling for baseline characteristics such as vaccination status, infection history, underlying medical conditions, socioeconomic factors, and preventive behaviors. Results: Overall, 81.6% of respondents received at least 1 dose of COVID-19 vaccine during the follow-up period. Among those without COVID-19 history at baseline (N = 19,182), 10.9% were diagnosed with COVID-19 in the past year, and 6.6% in the past 2 months. Respondents who received 1 or 2+ doses had lower diagnosis rates (APR = 0.76 and 0.43, respectively). For the past 2 months, only those with 2+ doses showed a significant reduction (APR = 0.51). Among 1999 diagnosed cases, those with 1 or 2+ doses showed lower hospitalization and oxygenation/ventilation likelihoods, though these differences were not statistically significant. Conclusions: The results supported the protective effect of COVID-19 vaccines against infection. Continued research is essential to further clarify the complex influence of vaccination, individual characteristics, and preventive behaviors on COVID-19 morbidity at the population level.

BACKGROUND: The present study aimed to investigate the association between the duration of anti-coronavirus disease 2019 (COVID-19) public health measures and the quality of life (QOL) and mental health of the Japanese public. METHODS: The present, nationwide, questionnaire-based, cross-sectional study was conducted in September 2021. The cumulative duration in days of anti-COVID-19 public health measures was calculated for each prefecture in the year prior to the survey, and multilevel linear regression analysis was used to determine the association between the duration of these measures and any impairment of QOL or mental health as assessed by the EuroQol 5-dimensions 5-levels (EQ-5D-5L) and the Kessler scale (K6). RESULTS: The study included 28 118 participants from all 47 prefectures. The median duration of public health measures of all prefectures was 179 days. Long-term duration of the measures (181-365 days) was not independently associated with low EQ-5D-5L (P = 0.128) or high K6 (P = 0.179) scores after adjusting for potential confounders (Graphical Abstract). CONCLUSIONS: Prolongation of the measures may not be associated with a deterioration in the QOL or mental health of the Japanese public. Nevertheless, it may be necessary to reconsider long-term public health measures given the potential they may have to cause collateral damage, such as socioeconomic one.