Tu228 - Comprehensive assessment of SARS-CoV-2 antibodies after COVID-19 infection and vaccination (BNT162b2 or ChAdOx1 nCoV-19) using multiplex bead assay

Abstract Text: Comprehensive assessment of SARS-CoV-2 antibodies is essential for monitoring after infection or vaccination. Thirty-two COVID-19 patients and forty naïve healthcare workers (HCWs) following two doses of Oxford–AstraZeneca (AZ) (n=20) or Pfizer–BioNTech (Pfizer) (n=20) vaccines were sequentially tested using multiplex bead-based assay (One lambda) (anti-full S, N, S1, S2, RBD), Roche (S1 RBD total Ig) and GenScript (neutralizing IgG). For COVID-19 patients, anti-S, S1 and RBD levels were higher than anti-S2 or N for 15-40 days after infection. Severe disease showed higher anti-S, S1, S2, and RBD levels than mild disease (p < 0.05). Comparing post-infection and post-prime vaccination, anti-S2, N and RBD levels were higher post-infection than post 1st-dose AZ vaccination. After 2nd-dose vaccination, anti-S, S1, S2 and RBD levels were higher in vaccinated HCWs (P < 0.05). Neutralizing antibodies levels were not different between post-infection and post-2nd-dose AZ group (P > 0.05). Comparing AZ and BNT group, 1st-dose BNT showed higher anti-full S, S2 and neutralizing antibody levels than 1st-dose AZ (P < 0.05). After boost vaccination, anti-full S, S1, RBD and neutralizing antibody levels were higher in BNT than AZ (P < 0.05). Evaluating intra-individual changes from post-prime to post-boost vaccination showed that AZ boost increased anti-S2 (3.5-fold) and neutralizing antibody (1.5-fold), and BNT boost increased anti-S1 (1.8-fold), S2 (1.5-fold), RBD (1.3 fold) levels. The dynamics and antibody levels assessed in natural infection and vaccination were assay-dependent. Understanding of vaccine versus infection-induced antibody responses will contribute to adjusting vaccination strategies and accelerating vaccination efficacy.