Pfizer says its vaccine works against key mutations on coronavirus variants found in South Africa, UK Jan 28, 2021, 03:16 PM facebook email Vera Leip, 88, receives a Pfizer-BioNtech COVID-19 vaccine at the John Knox Village Continuing Care Retirement Community on December 16, 2020 in Pompano Beach, Florida. Joe Raedle/Getty Images In a study, Pfizer and BioNTech's vaccine worked against lab-made coronaviruses similar to variants spreading in the UK and South Africa. Small differences in how the vaccine performed against the mutations, versus the original virus, were "unlikely to lead to a significant reduction" in effectiveness. The Pfizer-BioNTech vaccine hasn't been tested yet against the real-life coronavirus variants.