Assessment of the humoral response to the homologous Gam-COVID-Vac (Sputnik V) or heterologous Sputnik V/mRNA-1273 (Moderna) vaccination against SARS-CoV-2 in dialysis patients

IntroductionThe humoral response to vaccines is the most used tool to evaluate the protection against SARS-CoV-2 infection. Dialysis patients are a high-risk population and have a reduced immune response to vaccination.ObjectiveTo assess the humoral response to homologous Gam-COVID-Vac (Sputnik V) and heterologous Sputnik V/mRNA-1273 (Moderna) vaccination in dialysis patients.MethodsSARS-CoV-2 anti-spike IgG (RBD) concentration was estimated 3-16 weeks after complete vaccination. Reactogenicity was evaluated until day 7 by patients’ s self-reported side events.Results107 participants were enrolled [n=84 homologous (SpV/SpV), n=23 heterologous (SpV/Mod)]. Median (IQR) age was 64 (50-75) years old and 79 (73.8%) were male. Additionally, 19 (22.6%) of the SpV/SpV and 4 (17.4%) of the SpV/Mod group had a prior confirmed SARS-CoV-2 infection (p=0.589). In the overall population, 103 patients reached seroconversion (96.3%). Anti-S-RBD IgG median titers (IQR) were higher in the heterologous [1222 (288-5680) BAU/mL] than in the homologous scheme [447 (100-1551) BAU/mL], p=0.022. In a linear model adjusted for age and gender, previous SARS-COV-2 infection (B: 1944.3; CI95: 1136.2-2753.4; p<0.001), and SpV/Mod vaccination scheme (B: 1241.5; CI95: 420.39-2062.6; p=0.003) were independently associated with anti-S-RBD levels. Finally, a higher frequency of adverse effects was associated with the heterologous scheme, although they were well tolerated by all individuals.ConclusionThe present study provides evidence that the homologous SpV/SpV and heterologous SpV/Mod schemes showed good efficacy and safety under dialysis conditions. These results could be useful for future vaccination strategies, especially aimed at this risk group.