Airway antibodies wane rapidly after COVID-19 but B cell memory is generated across disease severity
AbstractUnderstanding immune responses following SARS-CoV-2 infection in relation to COVID-19 severity is critical for predicting the effects of long-term immunological memory on viral spread. Here we longitudinally assessed systemic and airway immune responses against SARS-CoV-2 in a well-characterized cohort of 147 infected individuals representing the full spectrum of COVID-19 severity; from asymptomatic infection to fatal disease. High systemic and airway antibody responses were elicited in patients with moderate to severe disease, and while systemic IgG levels were maintained after acute disease, airway IgG and IgA declined significantly. In contrast, individuals with mild symptoms showed significantly lower antibody responses but their levels of antigen-specific memory B cells were comparable with those observed in patients with moderate to severe disease. This suggests that antibodies in the airways may not be maintained at levels that prevent local virus entry upon re-exposure and therefore protection via activation of the memory B cell pool is critical.SummaryCOVID-19 severity determines the level of systemic and airway IgG and IgA but while IgG are maintained in plasma during convalescence, antibodies wane rapidly in the airways.However, comparable levels of antigen-specific memory B cells are generated across disease severity.