Antibody profile at baseline and during treatment
VIRUS
Antibodies were identified by class and ability to recognize the SARS-CoV-2 spike proteinSamples from the 1124 seropositive patients were tested for NAbs. Of these, 721 (64.0%) were NAb-positive, indicating that, although most seropositive patients had generated antibodies, a large proportion failed to generate functionally effective antibodies capable of virus neutralization. Of patients tested for NAbs who were only IgA-positive, 41.7% (222/532) were NAb-positive. In contrast, 91.4% (427/467) of patients who were both IgA- and IgG-positive were NAb-positive, consistent with anti-viral antibody responses reflecting the process of affinity maturationWe also evaluated the rate of seropositivity and NAb titers at baseline by risk factors for hospitalization, including age, sex, race, ethnicity, and viral load, in the Phase III portion of the trial (Supplemental Table 