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

Vickers, Molly A.; Sariol, Alan; Leon, Judith; Ehlers, Alexandra; Locher, Aaron V.; Dubay, Kerry A.; Collins, Laura; Voss, Dena; Odle, Abby E.; Holida, Myrl; Merrill, Anna E.; Perlman, Stanley; Knudson, C. Michael

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: Eleven recovered COVID‐19 patients were screened to donate CCP. All had molecularly confirmed COVID‐19, and all but one were antibody positive by chemiluminescence immunoassay (DiaSorin) prior to vaccination. All were tested again for antibodies 11–21 days after they were vaccinated (Pfizer/Moderna). 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 after 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.