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Background Confidence in natural immunity after infection with severe acute respiratory syndrome coronavirus 2 is one reason for vaccine hesitancy. Methods We measured antibody-mediated neutralization of spike protein-ACE2 receptor binding in a large community-based sample of seropositive individuals who differed in severity of infection (N = 790). Results A total of 39.8% of infections were asymptomatic, 46.5% were symptomatic with no clinical care, 13.8% were symptomatic with clinical care, and 3.7% required hospitalization. Moderate/high neutralizing activity was present after 41.3% of clinically managed infections, in comparison with 7.9% of symptomatic and 1.9% of asymptomatic infections. Conclusions Prior coronavirus disease 2019 infection does not guarantee a high level of antibody-mediated protection against reinfection in the general population. [ABSTRACT FROM AUTHOR]

Question: Is antibody response to COVID-19 mRNA vaccination similar in women and men?Findings: In a community cohort without prior COVID-19 infection, the first vaccine dose produced higher IgG levels and percent inhibition of spike-ACE2 receptor binding, a surrogate measure of virus neutralization, in women compared to men (7.0µg/ml; 51.6% vs 3.3µg/ml; 36.4%). After two doses, IgG levels remained significantly higher for women (30.4µg/ml) compared to men (20.6µg/ml), while percent inhibition was similar (98.4% vs 97.7%).Meaning: Sex-specific antibody response to mRNA vaccination informs future efforts to understand vaccine protection and side effects. [ABSTRACT FROM AUTHOR]

In a community-based sample of seropositive adults (n = 1101), we found that seropositive individuals who lived with a known coronavirus disease 2019 (COVID-19) case exhibited higher blood anti–severe acute respiratory syndrome coronavirus 2 spike receptor-binding domain immunoglobulin G concentrations and greater symptom severity compared to seropositive individuals who did not live with a known COVID-19 case. [ABSTRACT FROM AUTHOR]