The high seroconversion rate, calculated based on both S-IgG and S-IgA in our cohort, is similar to earlier studies of Sputnik-V2,10,19–21, and consistently, there was little benefit of Sputnik-V dose 2—limited to neutralizing Ab and mucosal S-IgG in participants without prior COVID-19. Here, CD79A is linked to COVID-19.