High-risk outing behaviors and COVID-19-related outcomes: A nationwide longitudinal study in Japan

In Japan, public health messaging during the COVID-19 pandemic emphasized avoiding "non-essential and non-urgent outings." However, empirical evidence linking specific outing behaviors to COVID-19 diagnosis or hospitalization remains limited.

We analyzed longitudinal data from 21,276 adults who completed both the 2021 and 2022 waves of the Japan "COVID-19 and Society" Internet Survey (JACSIS). Participants reported engagement in various social activities in 2021 and subsequent self-reported COVID-19 diagnosis or hospitalization by 2022. Activities were grouped into six domains: nightlife and entertainment venues, group recreational activities, private social gatherings at home, ceremonial or communal events, low-contact public spaces, and healthcare-related visits. Weighted logistic regression models simultaneously included all behavioral domains and adjusted for demographic, socioeconomic, health-related, and regional variables, as well as potentially protective factors including mask wearing, prior COVID-19 infection, and COVID-19 vaccination.

Overall, 10.2% of participants reported a COVID-19 diagnosis and 1.4% reported hospitalization. Frequent (≥1/month) visits to nightlife and entertainment venues were associated with higher odds of both COVID-19 diagnosis (aOR 1.74, 95% CI: 1.25-2.44) and hospitalization (aOR 3.86, 95% CI: 1.71-8.72). Monthly engagement in private social gatherings at home and ceremonial or communal events was also associated with COVID-19 diagnosis, although associations varied across outcomes.

Specific categories of social activities, especially nightlife-related behaviors, were associated with COVID-19 diagnosis and hospitalization, although these associations should be interpreted cautiously, given the potential influence of co-occurring behaviors and unmeasured factors. These findings support more precise, domain-specific public health messaging.