Yasmin Rafiei, B.Sc., and Michelle M. Mello, J.D., Ph.D.

On August 17, 2020, the Los Angeles Unified School District launched a program to test more than 700,000 students and staff for SARS-CoV-2. The district is paying a private contractor to provide next-day, early-morning results for as many as 40,000 tests daily. As of October 4, a total of 34,833 people had been tested at 42 sites. The program is notable not only because it’s ambitious, but also because it’s unusual: testing is conspicuously absent from school reopening plans in many other districts. Typically, exhaustive attention has instead focused on physical distancing, face coverings, hygiene, staggering of schedules, and cohorting (dividing students into small, fixed groups). Although the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics, the National Academies of Sciences, Engineering, and Medicine, and state officials have urged schools to prepare for Covid-19 cases, they have offered strikingly little substantive guidance on testing. Immediate attention to improving testing access and response planning is essential to the successful reopening of schools.

Available guidance documents typically instruct schools to gain access to testing by contacting local public health departments, and few schools appear to have solidified a strategy — especially one that extends beyond testing of symptomatic persons. For instance, public schools in Boston and in Miami-Dade County will not conduct screening testing and are placing responsibility on parents for testing symptomatic children. New York State strongly recommends that schools not conduct testing. However, after its teachers union threatened to strike over safety concerns, New York City added monthly random screening testing for 10 to 20% of staff and students, with more frequent testing in hot spots.

Most reopening plans instead focus on screening for Covid-19 symptoms. Yet recent research indicates that symptom screening alone will not enable schools to contain Covid-19 outbreaks.1 Because an estimated 40% of Covid-19 cases are asymptomatic and 50% of transmissions occur from asymptomatic persons, we believe that screening testing is critical. Nevertheless, until October 13, the CDC recommended against screening testing in schools, citing constraints on testing capacity and the unavailability of real-world studies of its effectiveness. The newer guidance states that schools “might choose” to offer voluntary testing and that their decisions “should be guided by what is feasible, practical, and acceptable” and should prioritize symptomatic persons and close contacts of persons diagnosed with Covid-19.

SARS-CoV-2 testing presents at least three challenges for schools. The first is access to testing. Disparities in access persist, particularly for people without severe symptoms or known Covid-19 contacts. Whereas many universities can provide testing using their own labs, K–12 schools are reliant on either public health departments or private contracting. They face formidable financial barriers to providing direct access to testing for students given other pandemic-related strains on their budgets, including state requirements to test employees. Costs of individual tests in the community range from $50 to $200,2 and federal law does not require employers or insurers to pay for SARS-CoV-2 screening tests administered as part of a return-to-work or return-to-school strategy. Congressional funds for testing the uninsured are also limited to tests for “diagnostic” purposes.

A second major challenge is the lag time in receiving test results. The latest available survey data, from August 2020, indicate that only 26% of tested Americans received their results within a day; 35% waited 4 or more days.3 With limited access to rapid diagnostic tests, screening testing for students and school staff will involve similar wait times. Even outside the high-contact setting of schools, delays in returning results have disturbing consequences: a modeling study showed that same-day results can prevent 80% of new transmissions, whereas a 7-day delay stops only 5%.4

Disparities among communities in testing access and lag times exacerbate preexisting socioeconomic and racial inequities among schools. Schools that cannot quickly obtain test results are disproportionately forced to rely on extended quarantines. Given the distinctive difficulties students from low-income households face in distance learning, these disparities are particularly troubling. They also disproportionately burden children with special health needs, who may be at higher risk of Covid-19 infection and may depend on school-based services.

Moreover, schools must ensure timely reporting of test results, which labs cannot legally disclose without authorization. Schools could counsel parents and secure their legal authorization to have their Covid-19 test results released directly to school officials or could ask parents to disclose those results to the school themselves. Alternatively, schools could build a rapid-feedback loop among testing laboratories, the public health department, and potential contacts, in accordance with public health exceptions to privacy laws. There is no indication that these steps are part of schools’ plans, however.

Third, implementing recommended responses to positive SARS-CoV-2 test results is logistically daunting. Screening testing involves a potentially large number of both true positive and false positive results, and the best practice is to isolate persons with positive results and quarantine in-school contacts until those persons test negative or the incubation period has elapsed. In schools not using cohorting, quarantines may affect a large number of students and staff. For example, a high school in Cherokee County, Georgia, had to quarantine more than a quarter of its 1800 students and suspend in-person learning after 25 students tested positive. Thus, in addition to arranging quarantines, schools must be able to deliver remote education to confined students on short notice.

Because testing-related challenges pose a serious threat to the viability of school reopening plans, we believe that increasing routine screening using rapid tests in schools should rank among our most urgent national priorities. In September, the federal government purchased 150 million rapid antigen tests for schools, but this effort falls short: one analysis estimated that K–12 schools would deplete this supply in 19 days if most students and staff were tested one to two times per week. Future Covid-19 relief packages should provide appropriations and technical assistance for schools to scale up testing programs, prioritizing districts with the least resources and the highest community risk. Congressional leaders and the White House have reportedly agreed on a “national testing strategy” as part of a proposed economic relief bill, but it is unclear what role, if any, school testing plays in it.

The federal government can also help by continuing to fund development of novel tests, including rapid antigen and saliva-based tests, and by strengthening efforts to ensure swift, broad, and equitable distribution. Investments by the National Institutes of Health and other sponsors have already spurred promising innovations. Several labs have been granted emergency use authorization to test saliva, including one product that has an open-source protocol and can be implemented using $4 worth of materials per test.

There is a strong rationale for instituting screening testing in schools, in places where adequate testing capacity exists. The CDC’s observation that such testing has not been systematically studied will remain true until a program is implemented, but we would argue that modeling studies provide ample evidence for moving forward now and evaluating results. In communities with a low prevalence of Covid-19, pooled testing — in which individual samples are grouped for analysis and, if positive, retested individually — can increase the feasibility of mass testing.3,5

State and local governments can assist schools by formulating concrete plans for mass testing and prompt return of results. In districts where schools must rely on testing through private physicians and labs, obtaining patients’ authorization for disclosure of results, instituting a strong feedback loop, and emphasizing the need for speed in students’ testing are paramount, given the risk of onward transmission.

Some observers have suggested that students from high-risk households (such as those in poorer neighborhoods) be offered more frequent testing than others.3 Targeted screening yields higher positivity rates, is more cost-effective than universal screening, and may help stem outbreaks in vulnerable communities. However, these benefits must be balanced against the potential for stigmatization. Different communities will weigh these considerations differently.

As schools continue to refine their reopening plans, in addition to strengthening testing, they will have to assume an ongoing need for providing remote education due to quarantines. They should also expect fluctuations in the cohort of students receiving such education. Many K–12 schools have staffed distance-learning programs under the assumption of a constant volume, based on surveys eliciting parents’ preferences concerning return to school. In reality, student numbers will be in constant flux. Without planning, this variability could compromise educational continuity.

Finally, return-to-school standards should be linked to Covid-19 community transmission rates. As long as schools are unable to conduct testing at scale, the success of reopening will be heavily determined by rates of disease in the community. Without a comprehensive reopening strategy that incorporates testing as a key pillar, school reopening plans will not make the grade.

Disclosure forms provided by the authors are available at NEJM.org.

This article was published on October 21, 2020, at NEJM.org.

Author Affiliations

From Stanford University School of Medicine (Y.R., M.M.M.) and Stanford Law School (M.M.M.), Stanford, CA.

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