By Faye Flam / Bloomberg Opinion
The Food and Drug Administration needs a new covid vaccine policy that follows the latest immunology and vaccine efficacy data. At a meeting scheduled for Thursday, the agency should acknowledge booster shots aren’t having much effect on the spread of covid. Pushing them on young, healthy people is a waste of resources and a drain on public trust.
If given at the right time, the boosters still decrease the odds of getting severely ill or dying; and any policy going forward has to focus on the people most at risk. But the ideal timing is complicated, and getting more shots isn’t necessarily better. The FDA’s plan, according to early reports, is to push boosters every fall, like flu shots; which makes sense for those at low risk but might not suit those over 75, who might benefit from more frequent shots.
Currently, the U.S. government has switched to a reformulated, “bivalent” booster; and the FDA has authorized the use of the Moderna version for everyone over six months of age and more than two months past the previous shot. While the FDA has authority over who can get which vaccine, the Centers for Disease Control and Prevention has made a recommendation that everyone get all the boosters they’re eligible for, though it does suggest people who were recently infected can wait three months from the onset of symptoms. But some immunologists say a booster will have only marginal benefit if given just two months after a previous shot (or three after an infection).
“The longer you wait, the better the boost,” says Dan Barouch, a vaccine researcher at Harvard Medical School and Beth Israel Deaconess Medical Center, and a lead developer of the Johnson & Johnson vaccine. “If you get the booster two to three months after [a past boost] you really have a marginal benefit,” he said. “If you wait eight months, then you have at least a short-term benefit of 40 percent to 50 percent.”
Barouch pointed to new CDC data that showed those who got the bivalent shot had a temporary protection against symptomatic illness of 28 percent to 31 percent, but those who waited more than eight months saw protection between 43 percent to 56 percent.
It’s not clear how long that protection lasts; or whether the people who waited eight months might get longer-lasting protection than those who rushed to get the new booster.
For some high-risk people, there’s a downside to waiting. “If you have an elderly person and they get critically ill three months from now because they didn’t get the booster, then obviously that’s not better off,” Barouch says.
Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, quoted that same CDC data in a recent New England Journal of Medicine opinion piece to argue that booster dosing is “probably best reserved for the people most likely to need protection against severe disease.”
He also pointed to a couple of disappointing studies of the new bivalent booster, which has been the only one available since September, reformulated with a component of the (no longer dominant) BA.4 and BA.5 variants. The studies showed it worked no better than the original booster. These were test-tube experiments using human serum and truncated versions of different variants. The shots have never been directly compared in a clinical trial.
It’s still a good boost, said Barouch, who is author of one of those studies; just not likely to be any more protective than the old one.
A recent, unpublished study out of the Cleveland Clinic reported that among health-care workers, those who got four shots had more infections than those who got three or two. Barouch said that doesn’t necessarily reflect a problem with subjects getting their shots spaced too close together. But it does mean we can’t assume that more shots are always better.
So, what’s the ideal timing for a booster for most people? “Well, the expert opinion is currently divided,” he said.
Immunologist Duane Wesemann of Harvard Medical School said he’s happy with the CDC’s current recommendation, as long as the public and doctors understand that a two-month wait is a minimum; and not optimal timing for most people.
He said he had a patient who had just recovered from covid a few weeks earlier, and who had had a rare allergic reaction to earlier shots, but nevertheless was being required by an employer to get a new booster. Wesemann said he managed to convince the employer to listen to reason. He doesn’t fault the CDC; the problem was with the employer for making the false assumption that anyone who doesn’t get as many shots as possible is a threat to others.
I asked him why timing would matter at all for boosters. He explained that there’s a slow process that happens in your immune system. After an infection or a vaccine, antibodies diversify, making a variety of slightly different versions of themselves. Waiting longer between shots means the boost will have more to work with; and will amplify the antibodies best suited to target the viral spike protein.
Wesemann hasn’t gotten the bivalent booster yet because he just had covid-19 in September. I, too, have waited because I also tested positive for a few days in September, have no comorbidities and am not elderly. Paul Offit said he skipped getting a second booster in 2022 because he got covid in the spring.
Some have worried about the prospect of immune imprinting; the idea that our immune systems are stuck on the original variant and aren’t responding to the new component of the bivalent booster. But Wesemann sees it differently. He points out that our immune systems and our now-outdated vaccines are keeping the hospitalization and death rates relatively low even with infections surging.
“Our immune system is still able to learn,” he said. “I get the sense from some of this debate out there that people think that their immune system is a lot dumber than it is.”
Back in 2021, getting vaccinated probably did serve to protect others by reducing the odds you’d get infected in the first place. That’s changed now that most antivaxxers have been infected, and new variants have allowed the virus to get around vaccine-induced immunity. The FDA should lead the shift away from one-size-fits-all mandates toward a more nuanced conversation about individual levels of risk.
Faye Flam is a Bloomberg Opinion columnist covering science. She is host of the “Follow the Science” podcast.
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