New data on Omicron BA.4/BA.5-adapted bivalent booster demonstrating improved immune response against emerging omicron sublineages. Pfizer + BioNTech SE.

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.