Abstract Title:

Risk of reinfection after seroconversion to SARS-CoV-2: A population-based propensity-score matched cohort study.

Abstract Source:

Clin Infect Dis. 2021 May 27. Epub 2021 May 27. PMID: 34043763

Abstract Author(s):

Antonio Leidi, Flora Koegler, Roxane Dumont, Richard Dubos, María-Eugenia Zaballa, Giovanni Piumatti, Matteo Coen, Amandine Berner, Pauline Darbellay Farhoumand, Pauline Vetter, Nicolas Vuilleumier, Laurent Kaiser, Delphine Courvoisier, Andrew S Azman, Idris Guessous, Silvia Stringhini,

Article Affiliation:

Antonio Leidi


BACKGROUND: Serological assays detecting anti-SARS-CoV-2 antibodies are being widely deployed in studies and clinical practice. However, the duration and effectiveness of the protection conferred by the immune response remains to be assessed in population-based samples. To estimate the incidence of newly acquired SARS-CoV-2 infections in seropositive individuals as compared to seronegative controls we conducted a retrospective longitudinal matched study.

METHODS: A seroprevalence survey including a representative sample of the population was conducted in Geneva, Switzerland between April and June 2020, immediately after the first pandemic wave. Seropositive participants were matched one-to-two to seronegative controls, using a propensity-score including age, gender, immunodeficiency, BMI, smoking status and education level. Each individual was linked to a state-registry of SARS-CoV-2 infections. Our primary outcome was confirmed infections occurring from serological status assessment to the end of the second pandemic wave (January 2021).

RESULTS: Among 8344 serosurvey participants, 498 seropositive individuals were selected and matched with 996 seronegative controls. After a mean follow-up of 35.6 (SD 3.2) weeks, 7 out of 498 (1.4%) seropositive subjects had a positive SARS-CoV-2 test, of whom 5 (1.0%) were classified as reinfections. In contrast, the infection rate was higher in seronegative individuals (15.5%, 154/996) during a similar follow-up period (mean 34.7 [SD 3.2] weeks), corresponding to a 94% (95%CI 86% to 98%, P<0.001) reduction in the hazard of having a positive SARS-CoV-2 test for seropositives.

CONCLUSIONS: Seroconversion after SARS-CoV-2 infection confers protection against reinfection lasting at least 8 months. These findings could help global health authorities establishing priority for vaccine allocation.

Study Type : Human Study

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Sayer Ji
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