WASHINGTON — The Biden administration now hopes to begin a Covid-19 boost campaign with retooled vaccines in September because Pfizer and Moderna have promised they can deliver doses by then, according to people familiar with the deliberations.
With updated formulations apparently close, federal officials have decided not to expand eligibility for second boosters of existing vaccines this summer. The new versions are expected to perform better against Omicron’s now-dominant BA.5 subvariant, although the data available so far is still preliminary.
At this time, only Americans over 50 and over 12 with certain immune deficiencies have been eligible for second booster doses. While some federal officials pushed to strengthen protections for younger Americans now, officials agreed on a goal of boosting everyone’s immunity in the fall with what is expected to be a more effective boost, before of a possible winter increase of the virus.
In internal deliberations, some senior health officials argued that eligibility for a second booster should be expanded before the reformulated version is ready because coronavirus infections are rising again. Dr. Anthony S. Fauci, the president’s chief medical adviser, and Dr. Ashish K. Jha, the White House’s pandemic response coordinator, defended that position.
“I think there should be flexibility and permissiveness to at least allow” a second booster for younger Americans, Dr. Fauci said in an interview this month. One alternative that was discussed was to offer the shots only to a younger and at-risk subset of people, such as pregnant women.
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But officials from the Food and Drug Administration and the Centers for Disease Control and Prevention argued that the government should focus on the fall campaign with updated doses, if the campaign could start soon enough. After Pfizer and Moderna recently assured the FDA that they could deliver millions of doses by mid-September, regulators decided it was better to wait for those injections.
All adults are expected to be eligible for the updated booster shots. Children could also be eligible, according to people familiar with the deliberations.
The federal government also plans to continue stressing that anyone who is eligible for additional shots should get them now and not wait until the fall. By midweek, health officials were still crafting their specific advice on the reformulated shots.
One of the concerns was to make sure people didn’t get a booster now followed by another with the updated formulation too soon. Officials worried that, especially for young men, two boosters in close succession could increase the risk of a rare heart-related side effect, myocarditis, which has been linked to both Pfizer’s and Moderna’s vaccines .
For other reasons, immunologists warn against receiving booster shots at short intervals.
“You can’t get vaccinated on Aug. 1 and get another one on Sept. 15 and expect the second vaccine to do anything,” said Shane Crotty, a virologist at the La Jolla Institute of Immunology. “You have so many antibodies lying around that if you get another dose, it won’t do anything.”
“The antibodies prevent the next dose from working” if the next dose is given too soon, he added, a pattern that also applies to other vaccines, such as tetanus or flu shots.
Federal officials were also concerned about the public’s patience with additional shots. The number of recipients has been decreasing with each new dose offered. While nearly half of those eligible for the first booster chose to get it, for example, less than 30 percent of eligible Americans have chosen to get the second booster, their fourth shot overall.
The Biden administration has been busy procuring the newly designed doses. The Department of Health and Human Services recently made an advance purchase of 105 million doses of the vaccine from Pfizer-BioNTech for $3.2 billion, scheduled for possible deployment in the fall. The administration is expected to finalize a similar deal with Moderna soon.
The government’s decision comes as cases of the highly contagious BA.5 variant remain high across the country. Deaths and hospitalizations have increased in recent weeks. The number of new cases announced each day has hovered around 130,000, likely a significant undercount due to the number of unreported domestic tests, and President Biden just had his own bout with the variant.
Deaths from Covid-19 are still heavily concentrated among older age groups, while hospitalizations remain well below the peak of the Omicron wave last winter.
At a late June meeting of an FDA advisory committee, independent vaccine experts overwhelmingly agreed on the need to update coronavirus vaccines because the virus is now more adept at evading protection . But both Pfizer and Moderna were reluctant to commit to delivering doses with a revised formulation in early fall.
Kathrin Jansen, Pfizer’s head of vaccine research, told the meeting that her company was ready to deliver doses in early October. Dr. Stephen Hoge, Moderna’s president, said his company might offer reformulated shots only in late October or early November.
But more recently, both companies assured federal officials they could speed up their schedules and be ready by early September, according to people familiar with the discussions.