Single-dose SARS-CoV-2 vaccine in a prospective cohort of COVID-19 patients

van Gils, M. J.; Willegen, H. D. G.; Wynberg, E.; Han, A. X.; van der Straten, K.; Verveen, A.; Lebbink, R.; Dijkstra, M.; Burger, J. A.; Oomen, M.; Tejjani, K.; Bouhuijs, J. H.; Appelman, B.; Lavell, A. H. A.; Poniman, M.; Caniels, T. G.; Bontjer, I.; van Vught, L. A.; Vlaar, A. P. J.; Sikkens, J. J.; Bomers, M. K.; Sanders, R. W.; Kootstra, N. A.; Russell, C. A.; Prins, M.; de Bree, G. J.; de Jong, M. D.; Group, RECoVERED Study

Background The urgent need for, but limited availability of, SARS-CoV-2 vaccines worldwide has led to widespread consideration of dose sparing strategies, particularly single vaccine dosing of individuals with prior SARS-CoV-2 infection. Methods We evaluated SARS-CoV-2 specific antibody responses following a single-dose of BNT162b2 (Pfizer-BioNTech) mRNA vaccine in 155 previously SARS-CoV-2-infected individuals participating in a population-based prospective cohort study of COVID-19 patients. Participants varied widely in age, comorbidities, COVID-19 severity and time since infection, ranging from 1 to 15 months. Serum antibody titers were determined at time of vaccination and one week after vaccination. Responses were compared to those in SARS-CoV-2-naive health care workers after two BNT162b2 mRNA vaccine doses. Results Within one week of vaccination, IgG antibody levels to virus spike and RBD proteins increased 27 to 29-fold and neutralizing antibody titers increased 12-fold, exceeding titers of fully vaccinated SARS-CoV-2-naive controls (95% credible interval (CrI): 0.56 to 0.67 v. control 95% CrI: -0.16 to -0.02). Pre-vaccination neutralizing antibody titers had the largest positive mean effect size on titers following vaccination (95% CrI (0.16 to 0.45)). COVID-19 severity, the presence of comorbidities and the time interval between infection and vaccination had no discernible impact on vaccine response. Conclusion A single dose of BNT162b2 mRNA vaccine up to 15 months after SARS-CoV-2 infection provides neutralizing titers exceeding two vaccine doses in previously uninfected individuals. These findings support wide implementation of a single-dose mRNA vaccine strategy after prior SARS-CoV-2 infection.