Comparison of molecular testing strategies for COVID-19 control: a mathematical modelling study
Fecha
2020Autor
C Grassly, Nicholas
Pons-Salort, Margarita
Parker, Edward P K
White, Peter J
Ferguson, Neil M
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Resumen
Background WHO has called for increased testing in response to the COVID-19 pandemic, but countries have taken
different approaches and the effectiveness of alternative strategies is unknown. We aimed to investigate the potential
impact of different testing and isolation strategies on transmission of severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2).
Methods We developed a mathematical model of SARS-CoV-2 transmission based on infectiousness and PCR test
sensitivity over time since infection. We estimated the reduction in the effective reproduction number (R) achieved by
testing and isolating symptomatic individuals, regular screening of high-risk groups irrespective of symptoms, and
quarantine of contacts of laboratory-confirmed cases identified through test-and-trace protocols. The expected
effectiveness of different testing strategies was defined as the percentage reduction in R. We reviewed data on the
performance of antibody tests reported by the Foundation for Innovative New Diagnostics and examined their
implications for the use of so-called immunity passports.
Findings If all individuals with symptoms compatible with COVID-19 self-isolated and self-isolation was 100% effective
in reducing onwards transmission, self-isolation of symptomatic individuals would result in a reduction in R of
47% (95% uncertainty interval [UI] 32–55). PCR testing to identify SARS-CoV-2 infection soon after symptom onset
could reduce the number of individuals needing to self-isolate, but would also reduce the effectiveness of self-isolation
(around 10% would be false negatives). Weekly screening of health-care workers and other high-risk groups irrespective
of symptoms by use of PCR testing is estimated to reduce their contribution to SARS-CoV-2 transmission by 23%
(95% UI 16–40), on top of reductions achieved by self-isolation following symptoms, assuming results are available at
24 h. The effectiveness of test and trace depends strongly on coverage and the timeliness of contact tracing, potentially
reducing R by 26% (95% UI 14–35) on top of reductions achieved by self-isolation following symptoms, if 80% of cases
and contacts are identified and there is immediate testing following symptom onset and quarantine of contacts within
24 h. Among currently available antibody tests, performance has been highly variable, with specificity around 90% or
lower for rapid diagnostic tests and 95–99% for laboratory-based ELISA and chemiluminescent assays.
Interpretation Molecular testing can play an important role in prevention of SARS-CoV-2 transmission, especially
among health-care workers and other high-risk groups, but no single strategy will reduce R below 1 at current levels
of population immunity. Immunity passports based on antibody tests or tests for infection face substantial technical,
legal, and ethical challenges.
Palabras clave
COVID-19; Mathematical modelling studyEnlace al recurso
https://doi.org/10.1016/Colecciones
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