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COVID-19 Infections among Students and Staff in New York City Public Schools

Our take —

In a large study of students and staff associated with New York City Public Schools, it was found that from October 2020 to December 2020 — when both hybrid learning (3 days in person/week) and fully remote learning options were being implemented — the school-based prevalence of COVID-19 was 0.4%. The cumulative incidence in schools was 341.1 cases per 100,000 from October 9, 2020 to November 19, 2020 (some hybrid learning) and 464.4 per 100,000 from December 7, 2020 to December 18, 2020 (primarily remote learning). Cumulative incidence associated with schools was consistently lower than that in the population overall. The secondary attack rate among school-based close contacts was low. With adequate COVID-19 mitigation strategies in place, the burden of COVID-19 was no higher in schools than in the general community. Lower attendance over this period and a study period which preceded the emergence and gradual takeover of SARS-CoV-2 variants in the population both suggest that results may change under different conditions, and consistent implementation of risk mitigation strategies remains important.

Study design

Retrospective Cohort

Study population and setting

From October 12 to November 20, 2020, students within New York City public schools were given the option of either hybrid (i.e., one to three days in-person per week) or fully remote learning. Schools then went fully remote, with only elementary and special education schools reopening in December. The goal of this study was to examine SARS-CoV-2 infections in students and staff within New York City public schools between October and December 2020. Three primary analyses were conducted: estimations of 1) the prevalence of SARS-CoV-2 from testing in schools, 2) the incidence of COVID-19 from testing in both schools and the community, and 3) the secondary attack rate based on monitoring of school-based close contacts. Cases were ascertained from three different sources: 1) mandatory reporting to the Department of Health and Mental Hygiene and subsequent interviews regarding school association; 2) school-affiliated individuals voluntarily notifying the school if they tested positive; 3) routine PCR testing of asymptomatic persons at schools (at least monthly at each school). School period-prevalence was defined as the number testing positive for SARS-CoV-2 divided by the total number of tests performed for a given school week. School incidence was defined as all cases reported across the whole period associated with in-person learning divided by the number of people estimated to be present in-person during that period. School cumulative incidence was calculated for two periods during the study period in order to account for the gap created by the Thanksgiving holidays. Prevalence and incidence estimates were compared to estimates derived from the larger community.

Summary of Main Findings

Among 234,132 individuals tested between October 9 and December 18, 2021, 0.4% tested positive (n=986), representing the period prevalence from in-school testing. Among students, test positivity was highest at elementary schools (n=355, 0.54%). Test positivity among those in secondary schools was 0.23%, n=5. From October 9 to November 19 (hybrid school was an option), the cumulative incidence in schools was 341.1 cases per 100,000, compared with 528.9 per 100,000 in the general population. From December 7 to December 18 (only elementary schools open), the cumulative incidence in schools was 464.4 cases per 100,000, compared with 509.6 per 100,000 in the general population. Among 36,423 school-based close contacts of confirmed cases, 191 (0.5%) tested positive.

Study Strengths

A major strength of this study was case ascertainment from three different sources: mandatory reporting, voluntary notification, and routine testing. Routine testing was done on a sample of asymptomatic individuals, mitigating selection biases caused by only the sickest individuals going in for testing.

Limitations

Findings from this study are based on routinely collected data, and there are some data missing due to lack of data availability, lack of consent for data access, etc. These results represent a short time period, in which there was either hybrid learning or fully remote learning; they also precede the emergence of an increasing prevalence of variant B.1.1.7 or the so-called New York variants in the population.

Value added

With mitigation approaches in place, including hybrid education and many students engaged in fully remote learning, there was no increased prevalence or incidence of SARS-CoV-2 in schools compared with the general community.

This review was posted on: 14 May 2021