february 2021 • JAMA Internal Medicine

Association of SARS-CoV-2 Seropositive Antibody Test With Risk of Future Infection

Harvey R., Rassen J., Kabelac C.

DOI: 10.1001/jamainternmed.2021.0366

Content curated by:David Rodrigues

Key message

Este estudo de coorte levante hipóteses interessantes. Desde logo que os pacientes com resultados de teste de anticorpos positivos eram inicialmente mais propensos a resultados positivos de PCR, consistentes com a ideia que existe presença prolongada de RNA na via respiratória após primo-infecção. No entanto tornaram-se marcadamente menos propensos a ter resultados positivos de PCR ao longo do tempo, sugerindo que a soropositividade está associada à proteção contra infecção. A duração da proteção é desconhecida e a proteção pode diminuir com o tempo.

Analysis

Population

Doentes que fizerem teste rápido de antigénios para a COVID-19

Method

Estudo de coorte de 3.2 milhões de pessoas nos EUA. Fizeram seguimento de pessoas com teste de antigénio positivo e compararam a incidência de infecção COVID-19 com o grupo que testarem negativo no teste de antigénio.

Results

3257478 pacientes únicos com um teste de índice de anticorpos; 56% eram mulheres com uma idade mediana (DP) de 48 (20) anos. Destes, 2876773 (88,3%) tiveram um resultado de anticorpo de índice negativo e 378606 (11,6%) tiveram um resultado de anticorpo de índice positivo. Durante os períodos de acompanhamento, a proporção (IC de 95%) de resultados PCR positivos entre os indivíduos que tiveram um teste de anticorpos positivo versus aqueles com um teste de anticorpos negativo foi de 2,85 (IC de 95%, 2,73-2,97) em 0 a 30 dias, 0,67 (95% CI, 0,6-0,74) em 31 a 60 dias, 0,29 (95% CI, 0,24-0,35) em 61 a 90 dias, e 0,10 (95% CI, 0,05-0,19) em mais de 90 dias.

Abstract

Importance Understanding the effect of serum antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on susceptibility to infection is important for identifying at-risk populations and could have implications for vaccine deployment. Objective The study purpose was to evaluate evidence of SARS-CoV-2 infection based on diagnostic nucleic acid amplification test (NAAT) among patients with positive vs negative test results for antibodies in an observational descriptive cohort study of clinical laboratory and linked claims data. Design, Setting, and Participants The study created cohorts from a deidentified data set composed of commercial laboratory tests, medical and pharmacy claims, electronic health records, and hospital chargemaster data. Patients were categorized as antibody-positive or antibody-negative according to their first SARS-CoV-2 antibody test in the database. Main Outcomes and Measures Primary end points were post-index diagnostic NAAT results, with infection defined as a positive diagnostic test post-index, measured in 30-day intervals (0-30, 31-60, 61-90, >90 days). Additional measures included demographic, geographic, and clinical characteristics at the time of the index antibody test, including recorded signs and symptoms or prior evidence of coronavirus 2019 (COVID) diagnoses or positive NAAT results and recorded comorbidities. Results The cohort included 3 257 478 unique patients with an index antibody test; 56% were female with a median (SD) age of 48 (20) years. Of these, 2 876 773 (88.3%) had a negative index antibody result, and 378 606 (11.6%) had a positive index antibody result. Patients with a negative antibody test result were older than those with a positive result (mean age 48 vs 44 years). Of index-positive patients, 18.4% converted to seronegative over the follow-up period. During the follow-up periods, the ratio (95% CI) of positive NAAT results among individuals who had a positive antibody test at index vs those with a negative antibody test at index was 2.85 (95% CI, 2.73-2.97) at 0 to 30 days, 0.67 (95% CI, 0.6-0.74) at 31 to 60 days, 0.29 (95% CI, 0.24-0.35) at 61 to 90 days, and 0.10 (95% CI, 0.05-0.19) at more than 90 days. Conclusions and Relevance In this cohort study, patients with positive antibody test results were initially more likely to have positive NAAT results, consistent with prolonged RNA shedding, but became markedly less likely to have positive NAAT results over time, suggesting that seropositivity is associated with protection from infection. The duration of protection is unknown, and protection may wane over time.