Subject(s)
COVID-19 , Immunity, Herd , COVID-19/prevention & control , COVID-19 Vaccines , Humans , SARS-CoV-2 , VaccinationABSTRACT
In response to a rapid rise in mortality within assisted living, facility-wide resident testing found 42% of 182 residents had SARS-CoV-2 infection; 68% of which were asymptomatic for 14 days before and after testing. Resident testing was a critical infection control measure needed to control transmission of SARS-CoV-2 infection.
Subject(s)
COVID-19 , SARS-CoV-2 , Asymptomatic Infections , Humans , Infection ControlABSTRACT
Passive transfer of antibodies from COVID-19 convalescent patients is being used as an experimental treatment for eligible patients with SARS-CoV-2 infections. The United States Food and Drug Administration's (FDA) guidelines for convalescent plasma initially recommended target antibody titers of 160. We evaluated SARS-CoV-2 neutralizing antibodies in sera from recovered COVID-19 patients using plaque reduction neutralization tests (PRNT) at moderate (PRNT50) and high (PRNT90) stringency thresholds. We found that neutralizing activity significantly increased with time post symptom onset (PSO), reaching a peak at 31-35 days PSO. At this point, the number of sera having neutralizing titers of at least 160 was approximately 93% (PRNT50) and approximately 54% (PRNT90). Sera with high SARS-CoV-2 antibody levels (>960 enzyme-linked immunosorbent assay titers) showed maximal activity, but not all high-titer sera contained neutralizing antibody at FDA recommended levels, particularly at high stringency. These results underscore the value of serum characterization for neutralization activity.