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COVID-19 in Primary and Secondary School Settings During the First Semester of School Reopening – Florida, August-December 2020

Our take —

Between August and December 2020, nearly 64,000 COVID-19 cases were detected among children ages 5-17 years in Florida, though 60% of these cases were not deemed to be school-related. During the study period, a median of 70% of registered students across districts attended full-time in-person school, and <1% of registered students were identified as having had school-related COVID-19. Factors associated with higher COVID-19 student case rates in a school district included earlier in-person reopenings, absence of mask mandates, and higher county-level background COVID-19 incidence. However, the validity of study findings are limited by possible misclassification of COVID-19 cases attributed to transmission within or outside of schools and the lack of adjustment for other SARS-CoV-2 control measures implemented within schools.

Study design


Study population and setting

The investigators estimated a student COVID-19 case rate for the state of Florida by dividing the number of confirmed COVID-19 cases in children aged 5-17 years by the total number of registered students in a school district. After estimating a COVID-19 student case rate between August and December 2020 for each school district, the investigators tested for associations between factors (e.g., date of reopenings, presence or absence of mask mandates, background COVID-19 incidence) and student COVID-19 case rates at the school district level.

Summary of Main Findings

From August 10 to December 21, 2020, 63,654 COVID-19 cases were reported among children ages 5-17 in Florida, 39.4% (n = 34,959) of which were classified as school-related cases (defined as a case who had been on school campus during the 14 days preceding symptom onset or testing, regardless of where the infection was acquired). Nearly 700 SARS-CoV-2 clusters were detected in approximately 10% of Florida’s 6,800 public schools; 110 of these outbreaks were attributed to extracurricular activities (i.e., sporting events, non-school-sanctioned gatherings, mass transit to school). Among 2,809,553 registered students in Florida, a median of 70% of students across Florida’s 67 school districts attended school in-person during the study period, yielding a median COVID-19 case rate of 1,280 cases per 100,000 registered students (school district range: 394–3,200). COVID-19 student case rates were significantly higher in school districts with earlier in-person re-openings (before August 16), with an absence of mask mandates in the school district re-opening plans, with smaller county population sizes, and with higher background county-level COVID-19 incidence.

Study Strengths

Contact tracing investigations were able to determine activities associated with a subset (81%) of outbreaks.


The procedure for determining whether COVID-19 cases were school-related depended on accuracy and completeness of case information, requiring detailed contact investigations in most instances; cases were, therefore, likely differentially misclassified based on factors like school district, testing availability, and completeness of contact investigations. Additionally, outside of mask mandates, the investigators did not explore or adjust for the impact of other control measures (e.g., classroom cohorting, quarantining of potentially exposed students and staff) on observed SARS-CoV-2 case rates in the study period. Because case rate estimates were aggregated for the entire study period (August to December 2020), the investigators could not examine how time-varying ecological factors (i.e., background COVID-19 incidence) impacted SARS-CoV-2 epidemic trajectories in school-aged children across school districts. Two of Florida’s largest school districts (Miami-Dade and Broward Counties) were excluded from analyses because of delayed school reopenings, which limits possible inference. Lastly, analysis at the school district level may have masked important differences in SARS-CoV-2 transmission and mitigation measures within individual schools.

Value added

This is among the first studies to examine factors associated with SARS-CoV-2 burdens among school-aged children in the United States, during an initial phase of school reopenings when background COVID-19 incidence was high.

This review was posted on: 7 May 2021