Active surveillance of asymptomatic, presymptomatic, and oligosymptomatic SARS-CoV-2-infected individuals in communities inhabiting closed or semi-closed institutions

NICOLÁS M. AMBROSIS; PABLO MARTIN AISPURO; KEILA BELHART; DANIELA BOTTERO; RENÉE L. CRISP; MARÍA V. DANSEY; MAGALI GABRIELLI; OSCAR FILEVICH; VALERIA GENOUD; ALEJANDRA GIORDANO; MIN C. LIN; ANIBAL R. LODEIRO; FELIPE MARCECA; NICO PREGI; FEDERICO R. LENICOV; LUCIANA ROCHA-VIEGAS; ERIKA RUDI; GUILLERMO SOLOVEY; MARIA E. ZURITA; ADALI PECCI; ROBERTO ETCHENIQUE; DANIELA F. HOZBOR

frontiers in medicine

Frontiers

Lugar: Lausanne; Año: 2021

Background: The high COVID-19 dissemination rate demands active surveillance to identify asymptomatic, presymptomatic, and oligosymptomatic (APO) SARS-CoV-2-infected individuals. This is of special importance in communities inhabiting closed or semi-closed institutions such as residential care homes, prisons, neuropsychiatric hospitals, etc., where risk people are in close contact. Thus, a pooling approach―where samples are mixed and tested as single pools―is an attractive strategy to rapidly detect APO-infected in these epidemiological scenarios.Materials and Methods: This study was done at different pandemic periods between May 28 and August 31 2020 in 153 closed or semi-closed institutions in the Province of Buenos Aires (Argentina). We setup pooling strategy in two stages: first a pool-testing followed by selective individual-testing according to pool results. Samples included in negative pools were presumed as negative, while samples from positive pools were re-tested individually for positives identification.Results: Sensitivity in 5-sample or 10-sample pools was adequate since only 2 Ct values were increased with regard to single tests on average. Concordance between 5-sample or 10-sample pools and individual-testing was 100% in the Ct ≤ 36. We tested 4936 APO clinical samples in 822 pools, requiring 86%-50% fewer tests in low-to-moderate prevalence settings compared to individual testing.Conclusions: By this strategy we detected three COVID-19 outbreaks at early stages in these institutions, helping to their containment and increasing the likelihood of saving lives in such places where risk groups are concentrated.