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Pfizer-BioNTech Adapted Bivalent Booster Neutralizes Emerging Omicron Subvariants

New clinical findings suggest the Pfizer-BioNTech bivalent booster elicited more neutralizing antibody titers for all tested emerging Omicron sublineages, compared to their original COVID-19 vaccine.

This week, Pfizer-BioNTech shared positive results from an immune response analysis of their Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine. The findings suggest that the bivalent booster is effective against newer Omicron sublineages, including BA.4.6, BA.2.75.2, BQ.1.1 and XBB.1.

At 1 month after a 30-µg booster dose of Pfizer-BioNTech’s updated bivalent vaccine, Omicron BA.4/BA.5 neutralizing antibody titers increased 13.2-fold in in adults older than 55 years, and 9.5-fold in adults 18-55 years.

Pfizer-BioNTech shared these data on the preprint server bioRxiv. With these results, the biotech companies concluded that their bivalent vaccine elicits a greater increase in neutralizing antibodies against emerging Omicron subvariants than their original wild-type COVID-19 vaccine.

The results showed that after a booster dose of the Pfizer-BioNTech 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), 6.7-fold (95% CI: 4.4,10.2) against BA.2.75.2, 8.7-fold (95% CI: 5.7, 13.3) against BQ.1.1, and 4.8-fold (95% CI: 3.3, 6.9) against XBB.1.

Comparatively, with the original Pfizer-BioNTech COVID-19 booster vaccine, neutralizing antibodies against BA.4.6 increased 2.3-fold (95% CI: 1.9, 2.8), 2.1-fold (95% CI: 1.7, 2.5) against BA.2.75.2, 1.8-fold, (95% CI: 1.6, 2.2) against BQ.1.1, and 1.5-fold (95% CI: 1.3, 1.8) against XBB.1.

Notably, the safety and tolerability profiles of the bivalent booster are comparably favorable to the original Pfizer-BioNTech COVID-19 vaccine.

These findings are similar to earlier clinical data suggesting Pfizer-BioNTech’s bivalent booster produced a 13.2-fold increase in BA.4/BA.5 antibody titers, compared to pre-boosting levels, in persons 55 years and older. This evoked a BA.4/BA.5 response 4-fold higher than the original Pfizer-BioNTech vaccine.

Currently, a booster dose of Pfizer-BioNTech’s Omicron BA.4/BA.5-adapted bivalent COVID-19 vaccine is available for individuals 5 years and older under Emergency Use Authorization (EUA) by the US Food and Drug Administration (FDA).