Humoral responses to single-dose BNT162b2 mRNA vaccination in dialysis patients previously infected with SARS-CoV-2

Background: Seroconversion rates following infection and vaccination are lower in dialysis patients compared to healthy controls. There is an urgent need for the characterization of humoral responses and success of a single-dose SARS-CoV-2 vaccination in previously infected dialysis patients. Methods: We performed a dual-center study with 43 dialysis patients after BNT162b2 vaccination and 25 dialysis patients after PCR-confirmed COVID-19. Single-dose vaccination was performed in 13 previously infected patients. Anti-S1 IgG, neutralizing antibodies, and antibodies against various SARS-CoV-2 epitopes were measured 6 weeks after the first vaccination or onset of COVID-19 and 3 weeks after single-dose vaccination. Results: Previously infected patients without vaccination showed a significantly higher neutralizing capacity than patients vaccinated twice (median (IQR) percent inhibition 88.0 (71.5-95.5) vs. 50.7 (26.4-81.0);P=0.018). After one single vaccine dose, infected individuals generated 15-to 34-fold higher levels of anti-S1 IgG than age-and dialysis vintage-matched patients after infection or two-time vaccination with a median (IQR) index of 274 (151-791) compared to 18 (8-41) and 8 (1-21) (for both P<0.001). With a median (IQR) percent inhibition of 97.6 (97.2-98.9), the neutralizing capacity of SARS-CoV-2 antibodies was significantly higher in previously infected patients compared to other groups (for both P<0.01). Bead-based analysis showed high antibody reactivity against various SARS-CoV-2 spike protein epitopes after single-dose vaccination in previously infected patients. Conclusions: Single-dose vaccination in previously infected dialysis patients induced a strong and broad antibody reactivity against various SARS-CoV-2 spike protein epitopes with high neutralizing capacity.