Optimizing Benefits of Testing Key Workers for Infection with SARS-CoV-2: A Mathematical Modeling Analysis

• Published in: Clinical Infectious Diseases Vol. 71; no. 12; pp. 3196 - 3203
• Main Authors: Sandmann, Frank G, White, Peter J, Ramsay, Mary, Jit, Mark
• Format: Journal Article Web Resource
• Language: English
• Published: US Oxford University Press 15.12.2020
• Subjects: Asymptomatic Infections; COVID-19; Humans; Major; Models, Theoretical; SARS-CoV-2; COVID-19; SARS-CoV-2; isolation; RT-PCR; testing
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/cid/ciaa901

Abstract Background Internationally, key workers such as healthcare staff are advised to stay at home if they or household members experience coronavirus disease 2019 (COVID-19)–like symptoms. This potentially isolates/quarantines many staff without SARS-CoV-2, while not preventing transmission from staff with asymptomatic infection. We explored the impact of testing staff on absence durations from work and transmission risks to others. Methods We used a decision-analytic model for 1000 key workers to compare the baseline strategy of (S0) no RT-PCR testing of workers to testing workers (S1) with COVID-19–like symptoms in isolation, (S2) without COVID-19–like symptoms but in household quarantine, and (S3) all staff. We explored confirmatory re-testing scenarios of repeating all initial tests, initially positive tests, initially negative tests, or no re-testing. We varied all parameters, including the infection rate (0.1–20%), proportion asymptomatic (10–80%), sensitivity (60–95%), and specificity (90–100%). Results Testing all staff (S3) changes the risk of workplace transmission by −56.9 to +1.0 workers/1000 tests (with reductions throughout at RT-PCR sensitivity ≥65%), and absences by −0.5 to +3.6 days/test but at heightened testing needs of 989.6–1995.9 tests/1000 workers. Testing workers in household quarantine (S2) reduces absences the most by 3.0–6.9 days/test (at 47.0–210.4 tests/1000 workers), while increasing risk of workplace transmission by 0.02–49.5 infected workers/1000 tests (which can be minimized when re-testing initially negative tests). Conclusions Based on optimizing absence durations or transmission risk, our modeling suggests testing staff in household quarantine or all staff, depending on infection levels and testing capacities. RT-PCR testing of all staff reduces the risk of workplace transmission the most, but at increased staff shortages and testing resource needs. Testing staff in quarantine allows some staff to return to work but at slightly increased risk of workplace transmission.