Genetic Evidence and Host Immune Response in Persons Reinfected with SARS-CoV-2, Brazil

TLDR

SARS‑CoV‑2 reinfection dynamics are poorly understood. In a Brazilian cluster, patients experienced two COVID‑19 episodes; the first showed strong innate but incomplete humoral immunity, while the second involved distinct strains, higher viral loads, and symptoms, indicating that mild cases can control replication without detectable antibodies and that reinfection may be more common than assumed.

Abstract

Abstract The dynamics underlying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection remain poorly understood. We identified a small cluster of patients in Brazil who experienced 2 episodes of coronavirus disease (COVID-19) in March and late May 2020. In the first episode, patients manifested an enhanced innate response compared with healthy persons, but neutralizing humoral immunity was not fully achieved. The second episode was associated with different SARS-CoV-2 strains, higher viral loads, and clinical symptoms. Our finding that persons with mild COVID-19 may have controlled SARS-CoV-2 replication without developing detectable humoral immunity suggests that reinfection is more frequent than supposed, but this hypothesis is not well documented.