Pfizer Inc. and BioNTech SE announced results from an analysis examining the immune response induced by their Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine [Pfizer-BioNTech COVID-19 Vaccine, Bivalent (Original and Omicron BA.4/BA.5)] against newer Omicron sublineages, including BA.4.6, BA.2.75.2, BQ.1.1 and XBB.1. These data, posted on the preprint server bioRxiv, indicate that the companies' bivalent vaccine elicits a greater increase in neutralizing antibody titers than the companies' original COVID-19 vaccine against these emerging Omicron sublineages. Based on these findings, the Omicron BA.4/BA.5-adapted bivalent booster may help to provide improved protection against COVID-19 due to Omicron BA.4 and BA.5 sublineages as well as new sublineages that continue to increase in prevalence. Neutralization data were generated using a nonvalidated fluorescent focus reduction neutralization test (FFRNT) one month after administration of a 30-µg booster (fourth) dose of the companies' Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine or the original COVID-19 vaccine in adults aged 55 and older (approximately 40/vaccine group).

Sera were equally stratified by prior SARS-CoV-2 infection. Results showed the bivalent vaccine booster elicited a greater rise in neutralizing antibody titers for all tested Omicron sublineages compared to the original vaccine, regardless of prior SARS-CoV-2 infection status. Following a booster dose of the Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine, neutralizing antibodies against BA.4.6 increased 11.1-fold (95% CI: 7.1, 17.3), while neutralizing antibodies against BA.2.75.2, BQ.1.1, and XBB.1 increased by 6.7-fold (95% CI: 4.4,10.2), 8.7-fold (95% CI: 5.7, 13.3), and 4.8-fold (95% CI: 3.3, 6.9), respectively.

By comparison, the neutralizing antibody titers against BA.4.6, BA.2.75.2, BQ.1.1, and XBB.1 following a booster dose of the companies' original COVID-19 vaccine increased 2.3-fold (95% CI: 1.9, 2.8), 2.1-fold (95% CI: 1.7, 2.5), 1.8-fold, (95% CI: 1.6, 2.2), and 1.5-fold (95% CI: 1.3, 1.8), respectively. Overall, the bivalent booster generated a greater increase in neutralizing antibodies against emerging Omicron sublineages than the original Pfizer-BioNTech COVID-19 vaccine. These results are similar to recent clinical data showing the Omicron BA.4/BA.5-adapted bivalent booster evokes a 13-fold increase in BA.4/BA.5 neutralizing titers from pre-booster levels in individuals 55 years and older, resulting in a 4-fold higher BA.4/BA.5 response than the companies' original COVID-19 vaccine.

A booster dose of the Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine has been authorized for emergency use by the U.S. Food and Drug Administration (FDA) for ages 5 years and older and has been granted marketing authorization in the EU by the European Commission for ages 5 years and older. The Pfizer-BioNTech COVID-19 Vaccines (COMIRNATY®) are based on BioNTech's proprietary mRNA technology and were developed by both BioNTech and Pfizer. BioNTech is the Marketing Authorization Holder for BNT162b2 Wild Type and BNT162b2 Bivalent (Original/Omicron BA.4/BA.5) in the United States, the European Union, the United Kingdom, Canada and other countries, and the holder of emergency use authorizations or equivalents in the United States (jointly with Pfizer) and other countries.