In-person schooling has proved contentious and difficult to study throughout the SARS-CoV-2 pandemic. Data from a massive online survey in the United States indicates an increased risk of COVID-19-related outcomes among respondents living with a child attending school in-person. School-based mitigation measures are associated with significant reductions in risk, particularly daily symptoms screens, teacher masking, and closure of extra-curricular activities. A positive association between in-person schooling and COVID-19 outcomes persists at low levels of mitigation, but when seven or more mitigation measures are reported, a significant relationship is no longer observed. Among teachers, working outside the home was associated with an increase in COVID-19-related outcomes, but this association is similar to other occupations (e.g., healthcare, office work). While in-person schooling is associated with household COVID-19 risk, this risk can likely be controlled with properly implemented school-based mitigation measures.
The role of schools in transmission, and the value of school closure, has been one of the most contentious issues of the COVID-19 pandemic. There is ongoing debate about exactly how much SARS-CoV-2 risk is posed to individuals and communities by in-person schooling. While there is general consensus that it should be possible to open schools safely with adequate mitigation measures, there is little data and even less agreement as to what level of mitigation is needed.
Many ecological studies have shown an association between in-person schooling and the speed and extent of community SARS-CoV-2 transmission, though these results have not been uniform (4). While there have been numerous outbreaks in schools and school-like settings, studies outside of outbreak settings have suggested that, when mitigation measures are in place, transmission within schools is limited and infection rates mirror that of the surrounding community.
However, the ways in which in-person schooling influences community SARS-CoV-2 incidence are complex. Schools play a unique role in the social fabric of the United States and other countries, and often create potential transmission connections between otherwise disparate communities. Even if transmission in classrooms is rare, activities surrounding in-person schooling, such as student pick-up and drop-off, teacher interactions, and broader changes to behavior when school is in session could lead to increases in community transmission.
There is also a growing body of evidence that younger children (e.g., those under 10 years) are less susceptible to infection when exposed, though it is unclear if they are less likely to pass on the virus once infected, or if this reduced susceptibility is offset by increases in number of contacts during school. Even when school-aged children are infected, their risk of severe disease and death is low. This means that one of the main reasons for a focus on schools is not the risk to students, but the risk that in-person schooling poses to teachers and family members, and its impact on the overall epidemic. Yet, few studies have focused on the risk in-person school poses to household members.
Different interpretations of the evidence and local politics have led to massive heterogeneity in approaches to schooling across the United States during the 2020-21 school year, running the gambit from complete cessation of in-person learning to opening completely with no mitigation measures. Most schools that have opened have made some efforts to mitigate transmission, but there is much diversity in the approaches adopted.
This hodgepodge of approaches to schooling creates a natural experiment from which we can learn about what does, and does not, work for controlling school-associated SARS-CoV-2 spread. However, there is no central repository of the measures implemented across the over 130,000 schools in the United States, or health outcomes in these schools. Where data are available, they are often restricted to traditional public-school systems, though 28% of Pre-K through 12th grade students are in private or charter schools, and rarely can data be linked with individual- or household-level outcomes.
The COVID-19 Symptom Survey provides a unique opportunity to collect and analyze data on schooling behaviors and SARS-CoV-2 related outcomes from households throughout the United States. This survey is administered through Facebook in partnership with Carnegie Mellon University and yields approximately 500,000 survey responses in the United States weekly. It includes questions on symptoms related to COVID-19, testing and, since late November 2020, the schooling experience of any children in the household [survey details and questionnaires are available]. Analysis weights adjust for non-response and coverage bias (see materials and methods).
We analyzed data collected over two time periods during the 2020-2021 school year (Nov. 24, 2020-Dec. 23, 2020 and Jan. 11 2021-Feb. 10, 2021). Of 2,142,887 total respondents in the 50 US states and Washington DC during this period, 576,051 (26.9%) reported at least one child in Pre-K through high school living in their household (tables S1 and S2, Fig. 1A, and fig. S1). While larger states have more responses, the per-capita response rate was fairly consistent across states (20 per 100,000, range 10-29 per 100,000) and slightly higher in smaller states (fig. S2). Forty-nine percent (284,789/576,051) of these respondents reported a child living in the household engaged in either full- (68.8%) or part-time (46.0%) in-person schooling, with substantial variation both within and between states (Fig. 1 and table S3). Overall, in-person schooling increased between the two periods from 48% to 52%, though decreases were observed in some states (e.g., Arizona) (fig. S1 and table S3). Previous work has shown that household-reported rates of in-person schooling collected through the COVID-19 Symptom Survey track well with administrative data (19).
While we were not able to specifically examine the relationship between in-person schooling, mitigation measures and risk to teachers, we were able to assess the risk associated with reporting paid work outside the home among pre-K through high school teachers. Teachers working outside the home were more likely to report COVID-19-related outcomes than those working at home (e.g., Test positive aOR 1.8, 95% CI 1.5-2.2; fig. S15 and table S13). The confidence interval summarizing the elevation of risk overlapped with corresponding intervals associated with working in healthcare (aOR 1.7, 95% CI 1.5-1.9) and office work (aOR 1.6, 95% CI 1.5-1.7).
The results presented here provide evidence that in-person schooling poses a risk to those living in the households of students, but that this risk can be managed through commonly implemented school-based mitigation measures. This is consistent with findings from Sweden, where authors found risk to parents and teachers using a quasi-experimental approach. However, much remains unknown. We were unable to measure the risk posed by in-person schooling to the students themselves, nor were we able to specifically assess how different policies impact teachers and other school staff. While the interplay between school policies and local incidence is complex and, possibly, multi-directional, we find substantial variation in SARS-CoV-2 incidence regardless of the mean number of mitigation measures implemented within counties (figs. S8 and S15) and observed associations persist across study periods (figs. S17 to S19). This study also provides limited insight into the mechanisms by which in-person schooling increases risk, and it remains possible that classroom transmission plays a minor role, and other school-related activities drive risk.
This study has limitations. Measures of association between COVID-19 outcomes and key exposures may be biased if confounding factors were not fully accounted for. Though we adjust for several county-level measures of socioeconomic status, these data were not available at the individual level and are known to be associated with COVID-19 risk and attitudes about in-person schooling. Analyses stratified on urbanization, background COVID-19 risk, and propensity for in-person schooling (table S5) did not reveal substantial sensitivity to the levels of factors investigated, nor did examining alternative measures of individual and household COVID-19 occurrence (figs. S20 to S22), alleviating some of these concerns. Still, more formal studies that span schools with multiple policies and approaches would enhance insights into these questions.
Additionally, cross-sectional internet-based surveys have limitations and are subject to response biases. Although results are qualitatively consistent across COVID-19 outcomes [symptoms-based, test-based, and among those tested (figs. S20 to S22)], self-report has numerous limitations, for instance, we cannot robustly assess asymptomatic spread. We were also unable to evaluate compliance with or investment in reported mitigation measures, and there is potential for mitigation measures to be reported inaccurately on the survey. Survey respondents may not be representative of the full U.S. population, and while survey weights help account for non-response and coverage biases, weights calculated based on the Facebook user base were adjusted for representativeness of the wider population based only on age and gender, hence may not ensure representativeness across all covariates. However, the sample size of the survey and consistency of our findings across sub-analyses allay some of these concerns, as does assessment of non-COVID outcomes (figs. S23 and S24). Further, any response biases would have to be differential based on schooling status to bias our results away from the null.
The debate around in-person schooling in the United States has been intense, and has exacerbated differences in approach between independent school systems and individual families nationally. This lack of coordination has provided an opportunity to learn about the risks of in-person schooling, and the degree to which mitigation measures may reduce risk. The results presented here provide one dimension of evidence for decision makers to consider in the context of a complex policy landscape with many competing risks and priorities. While online surveys have their unique limitations, the wide reach of the COVID-19 Symptom Survey has allowed us to gather data from households engaged in heterogeneous schooling activities throughout the country in a way few other studies could. In analyzing these data, we find support for the idea that in-person schooling carries with it increased COVID-19 risk to household members; but also evidence that common, low cost, mitigation measures can reduce this risk.
Reference & source information: https://science.sciencemag.org/
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