School closures during spring in US linked to a massive decline in coronavirus cases and deaths, say researchers

Analysis says school-related spread may be mitigated with infection-control interventions recommended by the CDC such as frequent handwashing, universal masking and increased sanitation measures


                            School closures during spring in US linked to a massive decline in coronavirus cases and deaths, say researchers
(Getty Images)

As states across the US grapple with the issue of sending children back to the classrooms amid the pandemic, new estimates show that school closure may have been associated with more than one million fewer cases of Covid-19 and over 40,000 fewer deaths. States that closed schools earlier when they had fewer coronavirus cases had the largest relative reduction in overall incidence and death, says the research team from the Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine and Pediatric Research in Inpatient Settings Network, all based in Ohio. 

“School closure was associated with decreased Covid-19 incidence and death. These analyses do not incorporate the risks of school closure on child education and development or from a societal perspective. However, the analyses suggest that school closure may be effective in curbing Covid-19 spread and preventing deaths during future outbreaks,” write authors in the study published in JAMA. 

In the US, all 50 states closed schools between March 13, 2020 and March 23, 2020. The current population-based observational study was conducted between March 9 and May 7. The authors analyzed the cumulative incidence of Covid-19 in each state per 100,000 people at the time of school closures. The analysis shows that school closure was associated with a significant decline in both incidences of Covid-19 and deaths. The projections show that if schools had stayed open, there could have been roughly 424 more coronavirus infections and approximately 13 more deaths per 100,000 residents. Extrapolating these results to the US population, the authors estimate that school closure may have been associated with 1.37 million fewer cases of Covid-19 over 26 days and 40,600 fewer deaths over 16 days during the spring of 2020. The research team, however, says that it is possible that some of the reduction may have been related to other concurrent nonpharmaceutical interventions such as prohibiting large gatherings and closing nonessential businesses, restaurants and bars.

The research team says that it is possible that some of the reduction in Covid-19 cases and deaths may have been related to other concurrent nonpharmaceutical interventions such as prohibiting large gatherings and closing nonessential businesses and restaurants. (Getty Images)

“School closure was associated with a −62% relative change in Covid-19 incidence per week, corresponding to an estimated absolute difference of 423.9 cases per 100,000. School closure was associated with a −58% (relative change in mortality per week, corresponding to an estimated absolute difference in mortality of 12.6 deaths per 100,000. Extrapolating the absolute differences of 423.9 cases and 12.6 deaths per 100,000 to 322.2 million residents nationally suggests that school closure may have been associated with approximately 1.37 million fewer cases of Covid-19 over a 26-day period and 40,600 fewer deaths over a 16-day period,” write authors. They add, “In a model derived from this analysis, it was estimated that closing schools in states when the cumulative incidence of Covid-19 was in the lowest quartile compared with the highest quartile was associated with 128.7 fewer cases per 100,000 population over 26 days and with 1.5 fewer deaths per 100 000 population over 16 days.”

According to the team, the findings suggest that the timing of school closure plays a role in the “magnitude of changes” associated with curbing the spread. “As hypothesized, school closure in states that enacted this intervention early (when the cumulative incidence of Covid-19 was low) had greater associated relative decreases in incidence and mortality. Although these relative differences translate into smaller absolute differences associated with school closure, states that closed schools later (in the highest quartile of Covid-19 cumulative incidence) had more new cases and deaths from Covid-19 during the period after school closure,” say experts. They add, “Thus, this study can inform future decisions about optimal timing for state and local officials to consider school closure to curb Covid-19 spread in the high likelihood that the pandemic continues.”

The analysis does not elucidate mechanisms through which school closures might affect viral transmission. Whether the estimated associations between school closures and Covid-19 outcomes derive from reducing contacts among children or among their parents and caregivers, who are also less mobile, as a result, is not known. 

The authors acknowledge that it is unclear how coronavirus spread would be affected if schools remained open while states enacted other policies to restrict movement. They say it is possible school-related spread may be mitigated with infection-control interventions recommended by the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics, including frequent handwashing, universal mask policies, physical distancing measures and increased sanitation procedures. “However, given that school closure also alters adult behavior, decreasing Covid-19 spread within schools may be inadequate as a standalone intervention and may require continued alteration of adult interactions,” the authors caution.

The analysis does not elucidate mechanisms through which school closures might affect viral transmission. (Getty Images)

An editorial in JAMA on the current study says that school officials should consider the latest findings in the context of an evolving evidence base on Covid-19. However, it says that while the study suggests a role for school closures in virus mitigation, school and health officials must balance this with academic, health and economic consequences. 

The experts from the University of Pittsburgh suggest that bringing students back to school for in-person instruction may be feasible with a “precision public health approach.” Schools are considering hybrid online and in-person instruction, limiting after-school programs, and reconfiguring spaces, food preparation, and distribution. The editorial says that rather than a “one-size-fits-all recommendation,” school districts should rely on best available evidence including local Covid-19 prevalence, policies and practices regarding mask-wearing, and risk of transmission among children of different ages. 

“The decision to reopen schools for in-person educational instruction during the fall of 2020 is among the greatest challenges that the US has faced in generations. The decision will have life-long implications for millions of children and their families. In many parts of the country this has become a contentious issue, with children, their families, and teachers expressing strong opinions about what is best for them,” says the editorial. The experts emphasize that there has “rarely been a more important time for open discussion and collaboration with a goal of reaching consensus on reopening schools while protecting the health and well-being of students and educators” during the Covid-19 pandemic.

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