(HealthDay News) — New trial data suggest that Pfizer’s COVID-19 vaccine designed to target BA.4 and BA.5 is more powerful against the omicron subvariants than the original Pfizer-BioNTech COVID-19 vaccine, Pfizer announced last week.

“These early data suggest that our bivalent vaccine is anticipated to provide better protection against currently circulating variants than the original vaccine and potentially help to curb future surges in cases this winter,” Pfizer CEO Albert Bourla said in a company news release.

Blood samples taken from 80 people 1 week after they received the bivalent vaccine showed “a substantial increase” in their neutralizing antibody response against BA.4 and BA.5, which now account for 93% of all new US COVID-19 cases.


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The researchers did find that the antibody response in people older than 55 was “more limited” when faced with the omicron variants. Pfizer is conducting a similar comparison in younger adults.

Pfizer has also been testing the bivalent vaccine in mice. That research suggested the new vaccine provides at least “incremental benefit.”

Moderna, the only other company with a bivalent COVID-19 vaccine, has released results from its own mouse study, but the company has not commented on when it will have updated effectiveness data from clinical trials, CBS News reported.

When the US Food and Drug Administration (FDA) authorized the bivalent COVID-19 vaccines in September, it did so with the hope of getting ahead of a winter surge of the virus. At that time, advisers on the US Centers for Disease Control and Prevention vaccine advisory panel shared reservations they had about allowing boosters without the data in humans. However, FDA officials stressed that other vaccines are tested in the same way.

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