The analysis of serum IgA levels after SARS-CoV-2 infection combined with vaccination reveals for the first time that SARS-CoV-2 infection primes for a stronger IgA response after a single immunization with any of the three COVID-19 vaccines, than either two vaccinations in previously uninfected participants or a SARS-CoV-2 infection by itself. The gene discussed is CD79A; the disease is COVID-19.