The change shows that the FDA is trying to be more agile in its efforts to keep up with a changing virus. The precise formulation has yet to be tested in people, but studies have shown that vaccines adjusted to combat an earlier version of omicron modestly increased the short-term immune response in people compared to more injections of the original. The agency will rely in part on that data as it reviews new vaccines.
The FDA advised companies Thursday to create a two-part vaccine for a fall booster campaign. One part of the vaccine will be the original formulation, based on the version of the virus that spread globally in early 2020. The other part will be based on the omicron BA.4 and BA.5 subvariants that currently make up half of the strains. that are sequenced in the United States.
BA.4 and BA.5 may very well be overshadowed by new variants by the fall, but the hope is that a new shot will help broaden immunity as they are closer to where the virus is today. A Pfizer scientist showed data to FDA advisers on Tuesday that in mice, a vaccine based on those versions of omicron appeared to generate a stronger immune response.
For a year and a half, coronavirus vaccines based on the original version of the virus have provided strong protection, particularly against serious illness. But immunity wanes over time, and the virus has proven cunning, spawning a growing Greek alphabet of new variants that are more contagious and adept at escaping people’s immune defenses.
“As we move into the fall and winter, it is critical that we have safe and effective vaccine boosters that can provide protection against circulating and emerging variants to prevent the most serious consequences of covid-19,” said the FDA Statement said.
Experts have been distressed that such an important decision has to be made on the basis of very limited data. The change may provide a detectable increase in people’s protection against serious illness and perhaps also infection, but it is not certain.
“I think the FDA here is making a best guess about what they think is the right thing to do, and that may or may not turn out to be a good thing,” said John Moore, professor of microbiology and immunology at WeillCornell Medicine. “We don’t know and we have no real way of knowing.”
The modified vaccine will be used as a booster. People who are still getting their first shots will continue to get the original version of the vaccine.
people who are unvaccinated or without booster You shouldn’t put off vaccination in hopes of getting a new shot, particularly given the high levels of transmission, said an FDA official who requested anonymity because he wasn’t authorized to speak. People will still potentially be eligible for the fall booster, and all vaccines are better at protecting against serious illness and hospitalizations.
The federal government announced Thursday that it had agreed to buy 105 million doses of Pfizer’s restarted vaccine for 3.2 billion. At a dose of $30.50 per dose, that’s a premium over the initial contracts the government did for the original vaccine in 2020, when vaccines were $19.50 per dose.
Pfizer has said the price of its vaccine will likely go up after the pandemic, and that may not be the ceiling.
“We expect this to be only the second price increase between pandemic prices and future trading prices,” analysts at SVB Securities Research wrote in a note discussing the announcement.
Moderna Chairman Stephen Hoge told an FDA advisory committee that it would take his company until late October or early November to create a vaccine based on the BA.4 and BA.5 versions of omicron. It was unclear Thursday what the company’s timeline would be for supplying renewed doses to the United States.
