Infectious virus shedding duration reflects secretory IgA antibody response latency after SARS-CoV-2 infection

Infectious virus shedding from individuals infected with severe acute respiratory syndrome- coronavirus 2 (SARS- CoV-2) is used to estimate human to human transmission risk. Control of SARS-CoV-2 transmission requires identifying the immune correlates that protect infectious virus shedding. Mucosal immunity prevents infection by SARS- CoV-2, which replicates in the respiratory epithelium and spreads rapidly to other hosts. However, whether mucosal immunity prevents the shedding of the infectious virus in SARS- CoV-2- infected individuals is unknown. We examined the relationship between viral RNA shedding dynamics, duration of infectious virus shedding, and mucosal antibody responses during SARS-CoV-2 infection. Anti spike secretory IgA antibodies (S-IgA) reduced viral RNA load and infectivity more than anti spike IgG/IgA antibodies in infected nasopharyngeal samples. Compared with the IgG/IgA response, the anti spike S-IgA post- infection responses affected the viral RNA shedding dynamics and predicted the duration of infectious virus shedding regardless of the immune history. These findings highlight the importance of anti spike S-IgA responses in individuals infected with SARS-CoV-2 for preventing infectious virus shedding and SARS-CoV-2 transmission. Developing medical countermeasures to shorten S-IgA response time may help control human to human transmission of SARS-CoV-2 infection and prevent future respiratory virus pandemics.