ABSTRACT
The ongoing evolution of SARS-Co-V2 variants to omicron severely limits available effective monoclonal antibody therapies. Effective drugs are also supply limited. Covid-19 convalescent plasma (CCP) qualified for high antibody levels effectively reduces immunocompetent outpatient hospitalization. The FDA currently allows outpatient CCP for the immunosuppressed. Viral specific antibody levels in CCP can range ten-to hundred-fold between donors unlike the uniform viral specific monoclonal antibody dosing. Limited data are available on the efficacy of polyclonal CCP to neutralize variants. We examined 108 pre-delta/pre-omicron donor units obtained before March 2021, 20 post-delta COVID-19/post-vaccination units and one pre-delta/pre-omicron hyperimmunoglobulin preparation for variant specific virus (vaccine-related isolate (WA-1), delta and omicron) neutralization correlated to Euroimmun S1 IgG antibody levels. We observed a 2-to 4-fold and 20-to 40-fold drop in virus neutralization from SARS-CoV-2 WA-1 to delta or omicron, respectively. CCP antibody levels in the upper 10% of the 108 donations as well as 100% of the post-delta COVID-19/post-vaccination units and the hyperimmunoglobulin effectively neutralized all three variants. High-titer CCP neutralizes SARS-CoV-2 variants despite no previous donor exposure to the variants. Key pointsAll of the post-delta COVID-19/post vaccination convalescent plasma effectively neutralizes the omicron and delta variants. High-titer CCP and hyperimmunoglobulin neutralizes SARS-CoV-2 variants despite no previous donor exposure to the variants.
ABSTRACT
The prevalence and longevity of acquired immunity to coronavirus disease 2019 (COVID-19) in health care workers (HCWs) is of great interest, especially with the roll-out of vaccines for SARS-CoV-2. Determining such immunity may enhance knowledge about susceptibility of HCWs to COVID-19, frequency of vaccine administration, and degree of workplace risk, and may also support enactment of better workplace policies and procedures. The present study reports on 6-months follow-up serosurveillance to determine the longevity of SARS-CoV-2 antibodies in HCWs. Sub-sample (n=35) of the original serosurveillance in HCWs (n = 3,458) with baseline, 8-week, and 6-month blood sampling were analyzed. Information on job duties, location, COVID-19 symptoms, polymerase chain reaction test history, travel since January 2020, and household contacts with COVID-19 was collected. Of 35 subjects, 13 were seropositive at baseline and maintained positivity at 8-week follow-up, with 3 losing positivity at 6-month follow-up. Among 22 subjects who were seronegative at baseline and seropositive at 8-week follow-up, all but one maintained positivity at 6-month follow-up. There was no significant effect of all factors (e.g., age, gender, job duties) examined at the .05 level on seropositivity at 6-month follow-up. The observed antibody longevity was 7.0+/-0.6 months for seropositive subjects (n=13), and 4.5+/-0.8 months for those seronegative subjects (n=22), at baseline. The longest duration of seropositivity observed in this cohort was 7.9 months (236 days). With reported COVID-19-related symptoms up to 4.7 months prior to baseline blood sampling, possibly longer antibody presence is suggested. Similarly, seropositivity at 6-month follow-up further suggests greater antibody longevity than observed in this study.
