SARS-CoV-2 BNT162b2 vaccine-induced humoral response and reactogenicity in individuals with prior COVID-19 disease.

BACKGROUND: Most subjects with prior COVID-19 disease manifest long-term, protective immune responses against re-infection. Accordingly, we tested the hypothesis that humoral immune and reactogenicity responses to a SARS-CoV-2 mRNA vaccine differ in subjects with and without prior COVID-19. METHODS: Health care workers (n=61) with (n=30) and without (n=31) prior COVID-19 disease received two, 30 µg doses of Pfizer BNT162b2 vaccine 3 weeks apart. Serum IgG antibody against the Spike receptor-binding domain (RBD); serum neutralizing activity; and vaccine reactogenicity were assessed longitudinally every 2 weeks for 56 days after the 1st injection. RESULTS: The COVID group manifested more rapid increases in Spike IgG antibody and serum neutralizing activity post 1st vaccine dose but showed little or no increase after the 2nd dose compared to the infection-naïve group. In fact, Spike IgG was maximum after the 1st dose in 36% of the COVID group versus 0% of the infection-naïve group. Peak IgG antibody was lower but appeared to fall more slowly in the COVID-19 versus the infection-naïve group. Finally, adverse systemic reactions e.g., fever, headache and malaise, were more frequent and lasted longer after both the 1st and 2nd injection in the COVID group than in the infection-naïve group. CONCLUSION: Subjects with prior COVID-19 demonstrate a robust, accelerated humoral immune response to the 1st dose but attenuated response to the 2nd dose of BNT162b2 vaccine compared to controls. The COVID-19 group also experiences greater reactogenicity. Humoral responses and reactogenicity to BNT162b2 differ qualitatively and quantitatively in subjects with prior COVID-19 compared to infection-naive subjects. FUNDING: This work was supported by Institutional Funds.