COVID-19 in Washington K-12 Schools: Time to first COVID-19 school outbreak characterized by learning modality and community transmission

BACKGROUND: There is limited research available on COVID-19 outbreaks in K-12 schools, and many schools will be looking for guidance on safely keeping schools open for the 2021-2022 school year. The primary purpose of this study was to examine the relationship between learning modality and time to assess whether there was a relationship between community level transmission and time to COVID-19 outbreak in schools.
METHODS: This study used data from the Washington State Department of Health (DOH) School Outbreak Assessment of Policies and Practices (SOAPP) survey. This is a retrospective survey designed to learn about school outbreaks and to assess the effectiveness of certain COVID-19 mitigation measures in reducing transmission in the K-12 school setting. A time-toevent analysis using the Cox Proportional Model was conducted to compare the time to the first outbreak between different learning modalities. Time to outbreak was compared between outbreaks in 100% remote, remote with exceptions, hybrid, and traditional in-person settings. Secondary analyses included community transmission of COVID-19 in the Cox Proportional Model.
RESULTS: The time-to-event analysis for the first aim did not find an association between learning modality and time to first COVID-19 outbreak. This The Cox Proportional Hazards model for the second aim met all assumptions and flagged hybrid learning modality and low transmission rate as significantly associated with time to outbreak. The p-value for hybrid learning modality was 0.008 with a hazard ratio of 4.46 (95% CI: 1.86, 10.70), indicating a strong relationship between a hybrid learning modality and increased risk of an outbreak. The pvalue for low transmission rate was 0.0015 with a hazard ratio of 3.73 (95% CI: 1.65, 8.40), indicating a strong relationship between a low transmission rate and shorter time to outbreak.
CONCLUSIONS: Further research is needed to draw conclusions about the relationships between learning modality, community level transmission of COVID-19 and outbreaks in K-12 schools in Washington state.