COVID-19 symptom severity predicts neutralizing antibody activity in a community-based serological study.

Serological testing for SARS-CoV-2 IgG antibodies is used to assess their presence in blood samples from exposed individuals and provides a measure of the magnitude of immune response to infection. The measurement of neutralizing antibodies (NAbs) in particular provides information about the severity of prior infection and level of protective immunity against re-infection. Much of the work investigating the association between prior infection severity and NAb levels has been conducted among clinical populations, and less is known about this relationship in the general population.

Comparison of IgG and neutralizing antibody responses after one or two doses of COVID-19 mRNA vaccine in previously infected and uninfected individuals.

Background: Recent reports have suggested that among individuals previously infected with SARS-CoV-2, a single mRNA vaccine dose is sufficient to elicit high levels of immunity.

Methods: We compared anti-SARS-CoV-2 spike receptor binding domain (RBD) IgG antibody concentrations and antibody-mediated neutralization of spike-angiotensin-converting enzyme (ACE2) receptor binding following vaccination of non-hospitalized participants by sero-status and acute virus diagnosis history. Participants were analysed before and after mRNA vaccination (BNT162b2/Pfizer or mRNA-1273/Moderna) in a community-based, home-collected, longitudinal serosurvey in the Chicago area (USA); none reported hospitalization for COVID-19.