IE 11 is not supported. For an optimal experience visit our site on another browser.

Pfizer asks FDA to authorize updated booster shot

The updated shot targets the BA.5 subvariant of omicron, which is currently the dominant strain in the U.S.
A health worker administers a Pfizer-BioNTech booster shot in Jackson, Miss., on Feb. 8, 2022.
A health worker administers a Pfizer-BioNTech booster shot in Jackson, Miss., on Feb. 8.Rogelio V. Solis / AP file

Pfizer-BioNTech asked the Food and Drug Administration to authorize an updated version of its Covid booster designed to target the BA.5 omicron subvariant, the drugmaker announced in a release Monday.

Pfizer’s release was sparse on new details about the efficacy of the booster, but the company said studies in animals found that the vaccine generated an immune response against multiple versions of omicron, including BA.4 and BA.5. It is planning to start clinical trials in people this month, the statement said.

The request, covering people ages 12 and up, will now be considered by the FDA, which will review the data and is expected to grant emergency use authorization for the age group sometime in September.

Full coverage of the Covid-19 pandemic

If authorized, the company said it is prepared to immediately begin distribution of the shots.

Bill Hanage, a Harvard epidemiologist, praised the "remarkably quick" turnaround time for the new version of the vaccine, saying it normally takes years for shots to be developed and distributed. BA.5 only began spreading throughout the U.S. in early June.

The new vaccine will be "important," especially for folks vulnerable to severe infections, such as the elderly.

The updated shots are expected to be rolled out as part of a fall booster campaign ahead of a potential winter surge in Covid cases, White House Covid coordinator Dr. Ashish Jha said last week.

Pfizer’s so-called bivalent booster targets the omicron subvariants BA.4 and BA.5, as well as the original strain of the virus, in a single shot. BA.5 accounts for nearly 90% of new Covid cases in the United States, according to the Centers for Disease Control and Prevention.

In June, the company released clinical trial data on a different version of a bivalent shot, one that targeted the original omicron variant. That booster was shown to be safe and produced an immune response.

The FDA is allowing Pfizer to submit less data on the shot than it has for previous Covid vaccines. The agency released guidance last year that said modified vaccines that target new, emerging strains of the coronavirus may be authorized without the need for lengthy clinical trials.

Jesse Goodman of Georgetown University, a former FDA vaccine chief, said it "makes sense" to update the vaccines to target new variants circulating.

How effective Pfizer's new bivalent vaccine is compared to the existing vaccines remains unclear. Goodman said he specifically wants to see how well the vaccines perform against infections.

It is "likely" the immune responses in people will be similar to those seen in the animal studies, he said, but "it is not known until human data are available."

If the new version of the vaccine gives stronger protection against infection and severe illness, it could mitigate future Covid waves and perhaps “take pressure off stretched healthcare systems,” said Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto.

Still, he noted that the lack of data on the bivalent vaccine could make people more hesitant to get the shot in the near term, slowing vaccine uptake.

"If you want good vaccine uptake and you want public buy-in and public trust, you should have sound data to drive it," he said.

Moderna is also preparing to ask the FDA to authorize its bivalent vaccine that targets BA.4 and BA.5 as well as the original strain.

Monday's announcement comes as the existing booster shots, from Pfizer and Moderna, have been a poor match for omicron and its growing family of subvariants. The shots, which target the original coronavirus strain identified in Wuhan, China in late 2019, still offer strong protection against severe illness.

It's possible another vaccine update will be needed in the future, as new variants emerge, said Dr. Anna Durbin, a vaccine researcher at Johns Hopkins University. But, in the meantime, "having a bivalent vaccine that can specifically target omicron should reduce symptomatic illness and hopefully transmission."

Follow NBC HEALTH on Twitter & Facebook.