On Jan. 27, 2021, Pfizer and BioNTech announced results from in vitro neutralization studies of sera from individuals vaccinated with the Pfizer-BioNTech COVID-19 vaccine.

The sera neutralized SARS-CoV-2 with key mutations present in the UK and South Africa variants, as measured by studies conducted by Pfizer and the University of Texas Medical Branch (UTMB). The results were published on the preprint server bioRxiv and submitted to a peer-reviewed journal.