Researchers at the Department of Viroscience, Erasmus MC, National Institute for Public Health and the Environment, Amsterdam UMC, and the Weill Medical College of Cornell University studied humoral and cellular immune responses to the wild type SARS-CoV-2, the B.1.1.7 variant (U.K. variant) and the B.1.351 variant (South African variant) in health care workers vaccinated with the BNT162b2 (Pfizer-BioNTech) mRNA vaccine.