MONDAY, June 27, 2022 – Pfizer Inc. announced Saturday that it has two possible candidates that beat back Omicron infection more effectively than its original vaccine.

The news follows Moderna’s announcement last week that its Omicron booster shot showed greater protection against the highly contagious variant.

On Tuesday, the U.S. Food and Drug Administration’s scientific advisers will meet to debate whether to recommend updating existing vaccines to provide greater protection against spreading variants. As part of that process, the panel will be analyzing data on the updated shots from both companies.

Pfizer said Saturday that it was confident its new booster candidates are better than their predecessor.

“Based on these data, we believe we have two very strong Omicron-adapted candidates,” Pfizer CEO Albert Bourla said in a company statement.

In one new booster option, Pfizer targeted just Omicron. In the other, they combined Omicron protection with that of the original vaccine. The company also tested the current dosage of 30 micrograms and a higher dosage of 60 micrograms.

Both the combined shot and the Omicron-specific shot provided a substantial increase in Omicron antibodies in middle-aged and older adults who had received three previous COVID vaccine doses. About 1,200 people took part in the study.

The Omicron-only booster prompted the strongest antibody response.

However, some experts believe that the combo shot may be a better choice because it retains the original shot’s power while adding in extra protection against Omicron. One month after vaccination, those who received the combo shot had a nine-fold to 11-fold increase in Omicron antibodies — 1.5 times better than simply getting another dose of the original vaccine, Pfizer’s data showed.

Preliminary lab studies also showed an increase in antibodies against the newer Omicron variants BA.4 and BA.5, though at lower levels. Those subvariants have gained ground in the United States in recent weeks, now accounting for roughly 35% of new infections, up from 23% a week ago.

During Tuesday’s FDA panel meeting, vaccine advisers will also debate Moderna’s new “bivalent” booster, which targets Omicron. The company said it has been making shots of the vaccine, called mRNA-1273.214, before getting regulatory approval so it can be ready to ship doses out for the fall and winter, when health experts worry there could be another wave of COVID-19.

None of the booster shot studies were designed to track how well the boosters prevented COVID cases or how long they are protective, the Associated Press said.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19 vaccines.

SOURCE: Pfizer, news release, June 25, 2022; Associated Press

By Cara Murez and Robin Foster HealthDay Reporters

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