Exponential increase in neutralizing and spike specific antibodies following vaccination of COVID-19 convalescent plasma donors

Abstract

Background: With the recent approval of COVID-19 vaccines, recovered COVID-19 subjects who are vaccinated may be ideal candidates to donate COVID-19 convalescent plasma (CCP). Case Series: Three recovered COVID-19 patients were screened to donate CCP. All had molecularly confirmed COVID-19, and all were antibody positive by chemiluminescence immunoassay (DiaSorin) prior to vaccination. All were healthcare providers and were tested again for antibodies 11 to 21 days after they received the first dose of the vaccine (Pfizer). All showed dramatic increases (~50 fold) in spike-specific antibody levels and had at least a 20- fold increase in the IC50 neutralizing antibody titer based on plaque reduction neutralization testing (PRNT). The spike-specific antibody levels following vaccination were significantly higher than those seen in any non-vaccinated COVID-19 subjects tested to date at our facility. Conclusion: Spike-specific and neutralizing antibodies demonstrated dramatic increases following a single vaccination post COVID-19 infection which significantly exceeded values seen with COVID-19 infection alone. Recovered COVID-19 subjects who are vaccinated may make ideal candidates for CCP donation.

SARS-CoV-2 antibody changes in patients receiving COVID-19 convalescent plasma from normal and vaccinated donors

“…Of those receiving CCP from vaccinated donors, 3 were seronegative prior to the transfusion and all 3 were seropositive after transfusion. In those receiving CCP from vaccinated donors, the average post transfusion antibody level was 210 AU/ml, a value higher even than the average value seen in CCP donors who had recovered from COVID-19 [16].…”

“…Antibody results from these donors have previously been reported and the average value for antibodypositive unvaccinated donors was 82 AU/ml while the average antibody level from vaccinated donors was 4166 AU/ml [19].…”

“…The FDA modified the CCP donor criteria to allow for collection of CCP from vaccinated donors on January 15, 2021. At this time we refocused our CCP collection efforts exclusively on vaccinated donors as we found these donors had exponentially higher antibody levels [16]. While nearly 20 vaccinated CCP donors have been tested to date, CCP was only collected from 6 due to donor restrictions outlined under the FDA guidance.…”

“…While not a randomized trial, results from the expanded access protocol in the US (NCT04338360) demonstrate that hospitalized patients receiving high titer CCP had improved survival when compared to the low titer group [15]. Furthermore, recent reports have demonstrated that CCP donors who are vaccinated have dramatically higher spike-specific antibody levels with high neutralization titers than those that experience a natural infection [16,17]. Given this information, one could hypothesize that patients receiving high quality CCP from vaccinated donors may be more likely to respond clinically.…”

“…To begin to identify what makes some CCP units more effective than others, an IRB-approved protocol to collect and store plasma on CCP recipients before and after they were transfused was established. This protocol allowed us to directly measure the effects of individual CCP transfusions on antibody levels in patients receiving CCP units with a wide range of antibody levels [18][19][20]. While usage of CCP has declined, 4 subjects in our study have now received CCP from vaccinated donors.…”