On Dec. 8, 2021, Pfizer and BioNTech announced results from an initial laboratory study demonstrating that serum antibodies induced by the Pfizer-BioNTech COVID-19 Vaccine (BNT162b2) neutralize the SARS-CoV-2 Omicron variant after three doses.

Sera obtained from vaccinees one month after receiving the booster vaccination (third dose of BNT162b2 vaccine) neutralized the Omicron variant to levels that were comparable to those observed for the wild-type SARS-CoV-2 spike protein after two doses.