Updated July 26, 2022 at 11:17 AM ET

The Biden administration may scrap plans to let more younger adults get second COVID-19 boosters this summer. Instead, officials are trying to speed up availability of the next generation of boosters in the fall, NPR has learned.

The new strategy is aimed at trying to balance protecting people this summer with keeping people safe next winter, when the country will probably get hit by yet another surge.

But the possible shift is being met with mixed reactions. The Food and Drug Administration could make a final decision by the end of the week.

The dilemma facing the FDA is that the immunity many people have gotten from getting vaccinated or infected has been wearing off. At the same time, the most contagious version of the virus to emerge yet — the omicron subvariant BA.5 — is making people even more vulnerable.

So as COVID is starting to become more serious than a cold or flu again, most people younger than age 50 aren't eligible for fourth shots — second boosters — to protect themselves. In response, the FDA was considering opening up eligibility for second boosters for all adults.

But letting more people get boosted with the original vaccine now could interfere with plans to boost them with updated, hopefully more protective vaccines in the fall to blunt the toll of the winter surge.

That's why the administration is considering shifting the focus to the next generation of boosters. Moderna and Pfizer-BioNTech were already scrambling to comply with the FDA's request to get new, hopefully more powerful "bivalent" boosters ready by October or November that target both the original strain of the virus and omicron subvariants BA.4 and BA.5.

The FDA is trying to get the companies to make those shots available even sooner — possibly as soon as September, according to a federal official familiar with the situation who is not authorized to talk about it publicly. The possible shift was first reported by The Washington Post.

If the bivalent boosters can be accelerated, the FDA would skip opening up fourth shots of the original vaccines this summer and just wait for the new double-barreled omicron vaccines in the fall.

The possible shift is provoking mixed reactions.

Some think it is the smartest strategy. Three shots are still protecting most younger, otherwise healthy people against serious illness, they say. And boosting people again now, and then so soon again in the fall, could confuse people, potentially eroding their willingness to get any boosters, according to some experts.

"I think this will increase trust," Dr. Monica Gandhi, a professor of medicine at the University of California, San Francisco, wrote in an email to NPR. "We can't give a booster now and then again in 1.5 months or two months – that will decrease trust."

And giving two shots too close together could actually backfire from a health perspective, according to some experts.

"I think this is the right call," Dr. Celine Gounder, a senior fellow at the Kaiser Family Foundation, said during an interview with NPR. "If you get a booster now with the original formulation of the vaccine, this may in fact be counter-productive. It may prevent the second booster dose given this fall from taking and from you developing an immune response to that booster."

But others aren't so sure. They say the new vaccines may not be significantly better.

"People should not regard them as some sort of magic bullet that gives them super-strong protection," says Dr. John Moore, an immunologist at Weill Cornell Medicine. "These are not going to be magic bullet game-changers because they're not that much better than the already available vaccine boosters."

It's also unclear whether the new boosters can be ready by September. And who knows if BA.5 will even been the main virus by the fall and winter?

"I don't see the benefit waiting for a BA.5-specific booster since BA.5 may be in the rearview mirror and well past us by the time that's available," says Dr. Peter Hotez, dean of the Baylor College of Medicine National School of Tropical Medicine.

People younger than 50 should at least have the option to protect themselves now, especially with BA.5 already surging, some say.

"You're talking about you know literally hundreds of millions of people who are at a higher risk than they need to be for months," says Dr. Robert Wachter, chair of the department of medicine at the University of California, San Francisco.

"And that will mean potentially millions of preventable infections, certainly thousands of preventable hospitalizations, and probably hundreds of preventable deaths."

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