A staff member prepares a syringe with the Comirnaty vaccine from Biontech and Pfizer adapted to the Omicron-BA.1 variant at the vaccination center in Mainz.
Sebastien Christoph Gollnow | dfa | Image Alliance | Getty Images
Pfizer said its omicron booster triggers a stronger immune response against a number of emerging Covid subvariants circulating in the United States
The booster triggered more antibodies against the omicron BQ.1.1, BA.4.6, BA.2.75.2 and XBB.1 sublines in adults over 55 compared to a fourth dose of the original vaccines, according to new data released by the company on Friday. . Antibodies are a key part of the immune system that prevents the virus from invading cells.
Pfizer developed its booster against omicron BA.5 at the request of the Food and Drug Administration. BA.5 was the dominant Covid strain in the United States over the summer, but is now disappearing as subvariants such as BQ.1.1. start to become more dominant.
BQ.1.1 and its sibling BQ.1 are currently responsible for about 48% of new infections in the United States, according to data from the Centers for Disease Control and Prevention. BA.5, meanwhile, has declined to around 25% of new Covid cases. BA.4.6 and BA.2.75.2 still represent a very small proportion of new infections, while XBB.1 is not present in large enough numbers to appear in the data at this time.
Antibodies against BQ.1.1 were about nine times higher in people who received an omicron booster, while they were about twice as high in those who received a fourth dose of the original vaccine. Of the emerging subvariants, the omicron booster elicited the strongest immune response against BA.4.6 with 11-fold higher antibodies, and the weakest response against XBB.1 with approximately five-fold higher antibodies.
The booster triggers the strongest immune response against omicron BA.5, the variant against which it was designed, with antibodies increasing 13-fold in people over 55, according to data previously published by Pfizer.
Modern said on Monday that its omicron booster induces an immune response against BQ.1.1, although the company did not provide details.
US health officials said the boosters should offer better protection against emerging subvariants because they are all omicron and many are descended from BA.5.
New boosters from Pfizer and Moderna target both omicron BA.5 and the original Covid strain that emerged in Wuhan, China in 2019. The original vaccines only target the first Covid strain and their effectiveness has declined significantly against mild infections and illnesses as the virus has evolved in recent years.