Study population and setting
Evidence around whether transmission of SARS-CoV-2 occurs in schools has been challenging to generate. To answer this question, the authors used the COVID-19 Symptom Survey administered on Facebook which describes schooling behaviors and SARS-CoV-2 outcomes. Data from 2,142,887 respondents from November 24 to December 23, 2020 and January 11 to February 10, 2021 was analyzed. Of these, 576,051 had at least one child in school living in the household, of which in about half of households the child was attending either full or part time in-person schooling.
Summary of Main Findings
The study results showed that the risk of COVID-19-like illness was higher (adjusted OR 1.38, 95% CI 1.30-1.47) among those living with a child attending in person school compared to those who did not, and that the effect increased with increasing grade level of the child. Reports of mitigation measures at the school decreased the risk, with the strongest reduction associated with daily symptoms screens, teacher masking, and closure of extra-curricular activities. Implementation of 7 or more mitigation measures lead to almost no increased risk. In teachers, in-person teaching was associated with more COVID-19-related outcomes, but the risk was similar to that of other professions.
The study used a large survey database that included respondents all over the United States. The authors were able to control for a number of geographic differences between areas, including background incidence rates, that could potentially confound results.
Because the survey was administered through Facebook, results may not be fully generalizable to every part of the United States. Further the data are self-reported and may be subject to some mismeasurement. Finally, bias due to residual confounding remains possible as those areas that implemented the most mitigation measures may have had different risks before mitigation, even after adjusting for measured confounders.
This study is the largest to date in the US on transmission in schools, and suggests that in-person schooling does increase risk, but the risk can be minimized with strong mitigation measures.
This review was posted on: 22 March 2021