A prior COVID-19 infection affects the way the immune system responds to coronavirus shots. A Temple University study found people who were infected before vaccination only needed one dose of the Pfizer or Moderna vaccines to produce accelerated antibody levels. For others, it took two shots.
Scientists have shown that responses to the Pfizer-BioNTech BNT162b2 mRNA vaccine differ significantly in individuals based on whether or not they were previously infected with SARS-CoV-2.