Web-based real-time risk assessment of coronavirus disease 2019 infection in schools and social dining settings

Schools and dining situations are associated with a high risk of indoor transmission of coronavirus disease 2019 (COVID-19). Performing risk assessment in real time could enable organizers to adjust the duration and size of indoor activities depending on the epidemic situation.

The per-hour transmission rates of COVID-19 from a single infector in school and social dining settings were estimated from COVID-19 surveillance data in Japan from January to February 2022 using a mathematical model. We then developed a web application that calculates the risk of COVID-19 infection in those settings, accounting for place of residence, vaccination history, duration of indoor activity, and the number of participants.

The estimated per-hour transmission rates were 0.01934 (95 %CrI: 0.01939-0.01947) in social dining settings and 0.00324 (95 %CrI: 0.00323-0.00325) in school settings. Accounting for the epidemiological risk of having infected persons in indoor settings, a web application was devised to compute the risk of a single participant contracting COVID-19 at the event. Web application users can vary input variables including the duration and the number of participants, thereby benefiting the real time risk reduction.

The per-hour transmission rate was higher in social dining settings compared with that in school settings, but the greater number of participants that is typical of gatherings at schools might offset this gap in per-hour per-infector transmission risk. The proposed web application can act as an important tool for promoting risk awareness regarding COVID-19 in high-risk settings.