Asymptomatic COVID-19 screening tests to facilitate full-time school attendance: model-based analysis of cost and impact

BackgroundIn March 2021, the Biden administration allocated $10 billion for COVID-19 testing in schools. We evaluate the costs and benefits of testing strategies to reduce the infection risks of full-time in-person K-8 education at different levels of community incidence. MethodsWe used an agent-based network model to simulate transmission in elementary and middle school communities, parameterized to a US school structure and assuming dominance of the delta COVID-19 variant. We assess the value of different strategies for testing students and faculty/staff, including expanded diagnostic testing ("test to stay" policies that take the place of isolation for symptomatic students or quarantine for exposed classrooms); screening (routinely testing asymptomatic individuals to identify infections and contain transmission); and surveillance (testing a random sample of students to signaling undetected transmission and trigger additional investigation or interventions). Main outcome measuresWe project 30-day cumulative incidence of SARS-CoV-2 infection; proportion of cases detected; proportion of planned and unplanned days out of school; and the cost of testing programs and of childcare costs associated with different strategies. For screening policies, we further estimate cost per SARS-CoV-2 infection averted in students and staff, and for surveillance, probability of correctly or falsely triggering an outbreak response at different incidence and attack rates. ResultsAccounting for programmatic and childcare costs, "test to stay" policies achieve similar model-projected transmission to quarantine policies, with reduced overall costs. Weekly universal screening prevents approximately 50% of in-school transmission, with a lower projected societal cost than hybrid or remote schooling. The cost per infection averted in students and staff by weekly screening is lower for older students and schools with higher mitigation and declines as community transmission rises. In settings where local student incidence is unknown or rapidly changing, surveillance may trigger detection of moderate-to-large in-school outbreaks with fewer resources compared to screening. Conclusions"Test to stay" policies and/or screening tests can facilitate consistent in-person school attendance with low transmission risk across a range of community incidence. Surveillance may be a useful reduced-cost option for detecting outbreaks and identifying school environments that may benefit from increased mitigation.

Passing the Test: A model-based analysis of safe school-reopening strategies

BackgroundThe COVID-19 pandemic has induced historic educational disruptions. In December 2020, at least two-thirds of US public school students were not attending full-time in-person education. The Biden Administration has expressed that reopening schools is a priority. ObjectiveTo compare risks of SARS-COV-2 transmission in schools across different school-based prevention strategies and levels of community transmission. DesignWe developed an agent-based network model to simulate transmission in elementary and high school communities, including home, school, and inter-household interactions. SettingWe parameterized school structure based on average US classrooms, with elementary schools of 638 students and high schools of 1,451 students. We varied daily community incidence from 1 to 100 cases per 100,000 population. Patients (or Participants)We simulated students, faculty/staff, and adult household members. InterventionsWe evaluated isolation of symptomatic individuals, quarantine of an infected individuals contacts, reduced class sizes, alternative schedules, staff vaccination, and weekly asymptomatic screening. MeasurementsWe projected transmission among students, staff and families during one month following introduction of a single infection into a school. We also calculated the number of infections expected for a typical 8-week quarter, contingent on community incidence rate. ResultsSchool transmission risk varies according to student age and community incidence and is substantially reduced with effective, consistent mitigation measures. Nevertheless, when transmission occurs, it may be difficult to detect without regular, frequent testing due to the subclinical nature of most infections in children. Teacher vaccination can reduce transmission to staff, while asymptomatic screening both improves understanding of local circumstances and reduces transmission, facilitating five-day schedules at full classroom capacity. LimitationsThere is uncertainty about susceptibility and infectiousness of children and low precision regarding the effectiveness of specific prevention measures, particularly with emergence of new variants. ConclusionWith controlled community transmission and moderate school-based prevention measures, elementary schools can open with few in-school transmissions, while high schools require more intensive mitigation. Asymptomatic screening should be a key component of school reopenings, allowing reopening at higher community incidence while still minimizing transmission risk.

The operational impact of deploying SARS-CoV-2 vaccines in countries of the WHO African Region

BackgroundAfter SARS-CoV-2 vaccines become available, they will be deployed to many countries with limited immunization systems. MethodsWe conducted a cold chain capacity assessment of a simulated country in the WHO African Region. We combined region-specific data regarding immunization, population, healthcare workforce, and cold storage capacity (upper and lower range and quartile values for national and subnational levels). We used seasonal influenza vaccines as proxies for SARS-CoV-2 vaccines. We evaluated the increase in vaccine doses to be administered, doses administered per vaccinator, and cold storage volumes for SARS-CoV-2 campaigns targeting risk groups compared to routine immunization baselines. FindingsCompared to routine immunization, a SARS-CoV-2 vaccination campaign would increase monthly doses administered when targeting risk groups: [≥]65 years (29.9%), chronic diseases patients (101.5%), and healthcare workers (1.2%). SARS-CoV-2 vaccination campaigns would increase doses administered per vaccinator for risk groups: [≥]65 years (32.5%), chronic diseases patients (110.4%), or healthcare workers (1.4%). Routine vaccine volumes already exceed national level storage capacity for at least 75% of African Region countries, but subnational levels would have sufficient storage capacity for SARS-CoV-2 vaccines in all but the lower 25% of African Region countries. InterpretationSARS-CoV-2 vaccination campaigns would substantially increase doses per vaccinator and cold chain capacity requirements over routine immunization baselines. Pandemic vaccination campaigns would add volume to national level stores already at their limits, but substantial capacity exists at subnational levels for SARS-CoV-2 vaccines. Immediate attention to strengthening delivery systems is essential to support pandemic vaccine responses in the African Region. FundingNone