Study supports single-dose COVID-19 vaccine strategy for previously infected individuals Researchers in the Netherlands have provided evidence that a single dose of Pfizer-BioNTech’s coronavirus disease 2019 (COVID-19) vaccine is sufficient to protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among people who have already been infected with the virus. The urgent need for, but limited availability of, SARS-CoV-2 vaccines worldwide has led to widespread consideration of dose sparing strategies, particularly single vaccine dosing of individuals with prior SARS-CoV-2 infection,” says the team from the University of Amsterdam, the Public Health Service of Amsterdam and members of the RECoVERED Study Group.