Antibody responses boosted in seropositive healthcare workers after single dose of SARS-CoV-2 mRNA vaccine.

Current guidelines recommend that individuals who have had COVID-19 should receive the identical vaccine regimen as those who have not had the infection. This includes two doses of the mRNA platform vaccines (BNT162b2/Pfizer; mRNA-1273/Moderna) that are approved for use in the United States. In this brief report, we show that after a single dose of the Pfizer SARS-CoV-2 vaccine, individuals that had prior SARS-CoV-2 infection had significantly higher antibody levels than individuals that had no history of infection. This provides the rationale for changing vaccination policy to deliver only a single dose to individuals with recent SARS-CoV-2 infection that may free up additional doses for individuals that have no preexisting immunity to the virus. Future study of other immune parameters such as T cell response and durability of immune response should be rapidly undertaken in individuals that had COVID-19 prior to vaccination.