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Are you six months out from your Covid-19 bivalent booster and wondering when you’ll be able to get another shot?

If you live in the United Kingdom or Canada, you already have your answer. The Canadian and U.K. governments, acting on recommendations from expert committees, plan to offer spring booster shots for people at highest risk of getting severely sick from Covid.

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But in the United States, there’s been radio silence from the Food and Drug Administration on the question of spring boosters, creating frustration among a small but determined group of people who are keen not to have to wait until the autumn to get another dose of Covid vaccine.

“I will tell you that patients message me every day about this,” Camille Kotton, clinical director for transplant and immunocompromised host infectious diseases at Massachusetts General Hospital, told STAT in an interview.

Jamie Loehr, a family medicine physician in Ithaca, N.Y., has patients who got the updated booster shot last fall now asking him to give them off-label permission slips for a second bivalent jab.

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“There are people who are actively wanting regular updates on this,” Loehr said during a discussion on the future of Covid vaccination during the late February meeting of the Advisory Committee on Immunization Practices, a group of experts that advises the Centers for Disease Control and Prevention on vaccination policy. Loehr and Kotton are both members of the ACIP.

Despite the lack of guidance from the FDA, there is evidence that the agency was thinking about the issue even last fall. In an interview with STAT in October, Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, acknowledged he was worried one booster a year might not suffice for older adults and people who are immunocompromised.

“I would be lying to you if [I said] it doesn’t keep me up at night worrying that there is a certain chance that we may have to deploy another booster — at least for a portion of the population, perhaps older individuals — before next September, October,” Marks said at that time.

The FDA declined a request to interview Marks for this article. In an email, the agency sidestepped most of STAT’s questions, saying only on the issue of spring boosters that “We continue to closely monitor the emerging data in the United States and globally, and we will base any decision on additional updated boosters upon those data.”

The evidence to date suggests that Covid vaccines offer strong protection against severe disease, hospitalization, and death. But their capacity to stave off infection is short-lived.

With that in mind, the U.K.’s Joint Committee on Vaccination and Immunisation and Canada’s National Advisory Committee on Immunization have both issued recommendations that high-risk individuals should be offered the opportunity to get a Covid booster shot this spring.

In the U.K., where an astonishing 82.5% of people aged 75 and older received a bivalent booster last fall, the recommendation is that people who are 75 and older, or who live in a care home for older adults, or who are 5 years and older and are immunocompromised should be offered a spring booster, as long as it has been six months since their last shot.

“To protect the most vulnerable in the population against becoming seriously unwell with Covid-19, JCVI’s view is that the provision of a spring booster dose for these people is a proportionate response in 2023,” the group said in a statement.

In announcing the recommendation, the head of immunization for the U.K. Health Security Agency pointed to a recent uptick of severe cases among the elderly. “Covid-19 is still circulating widely, and we have recently seen increases in older people being hospitalized,” Mary Ramsey said.

NACI, the Canadian vaccine advisory group, recently voted to recommend that people should be allowed to get a spring booster if they are aged 80 or older, are adult residents of long-term care facilities, are 18 and older and are moderately or severely immunocompromised, or are aged 65 to 79, especially if they have no known history of previous Covid infection.

The U.K. recommendation is that the identified high-risk individuals “should” get another booster. The Canadian expert panel issued a softer recommendation, saying the high-risk people it highlighted “may” get an additional dose this spring, an approach that in the language of public health is called a “permissive” recommendation.

The latter approach is one some people would like to see adopted in this country. Loehr, the family medicine physician, told the February ACIP meeting he believes there should be annual Covid boosters but that people who are immunocompromised or aged 65 and older should have the option to get a second booster six months later, in consultation with a health care provider.

Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, would go further, saying people who are 50 and older in the U.S. should be offered the chance to get a second booster. He noted that in the second half of 2022, 97.3% of people who died from Covid in this country were aged 50 and older.

“That’s a pretty targeted group you can go at,” Osterholm said.

He acknowledged what’s obvious to anyone who has been tracking uptake of the bivalent booster in the U.S.: Doctors’ offices and pharmacies would not face a tsunami of people seeking a spring booster, if one were allowed. Only 16.3% of people eligible for the updated jab have received one; even among the highest-risk population, people aged 65 and older, fewer than half of those eligible — 41.6% — have gotten the shot.

“We currently live in a world where those that want additional booster doses really want them. And those that don’t want them don’t want them at all. And what we’re trying to do is thread that needle,” Osterholm said.

“I do think that given the data that we’ve seen on waning immunity over time, that if somebody wanted to be vaccinated every six months and if they were in a high-risk group by age or underlying health condition, then I think that should be permitted. I don’t believe for a moment that it will be a widespread practice.”

At the February meeting of the ACIP, members were told that the Covid vaccine work group, a subset of its members, had debated whether spring boosters should be recommended. But the group concluded it didn’t have enough evidence to say that another shot is needed at this time.

“The data weren’t conclusive to yet identify a need for frequent vaccines and there was concern that it may not be feasible to implement a vaccine program in all adults 65 and older twice a year,” Sara Oliver, a vaccine expert at the CDC, said at the meeting.

Oliver also noted, though, that the Covid work group recognized that older adults and people who are immunocompromised will likely remain more vulnerable to developing severe illness if they contract Covid, and there is probably a need to have more flexibility to address their situations going forward.

“I really like this idea about flexibility. And if the FDA decides that there can be some enhanced flexibility around the recommendations, I think that will be helpful,” MGH’s Kotton said during the discussion.

But that flexibility doesn’t currently exist. The bivalent Covid vaccines have not yet been licensed; they are being given under FDA Emergency Use Authorization. The rules around EUAs are strict. Products covered by EUAs can only be used in the way the FDA has ruled.

Once a vaccine is fully licensed, the ACIP has leeway to recommend use that differs from FDA’s licensing. For instance, though the FDA appears poised to license new respiratory syncytial virus vaccines for people 60 and older, the ACIP’s RSV work group signaled in February that cost-benefit analyses did not favor use of the vaccines in people aged 60 to 64.

With no clearance from FDA for a spring booster, ACIP is not able to recommend one.

Though there are avid proponents of spring booster shots, not everyone is convinced they are needed.

“With hospitalizations and deaths trending down, there is not movement towards a spring booster,” Kathleen Neuzil, director of the Center for Vaccine Development at the University of Maryland Medical School, said in an email.

Neuzil noted there are other tools for high-risk people who contract Covid — antiviral drugs. “These are underused for influenza … and we do not want them to be underused for Covid-19,” she said. “They are an important tool particularly for older persons and the immunocompromised, and people should be encouraged to contact their health care providers early in their illness.”

In the interview with STAT, Kotton noted that things have improved substantially for immunocompromised people — her patient base — since earlier in the pandemic. And that’s even though the monoclonal antibody product Evusheld, which had been used to help such patients avoid Covid infection, is no longer used because evolution of the virus that causes Covid has rendered it ineffective.

“I do want to say, big picture, we are seeing overall much lower rates of severe, life-threatening illness in immunocompromised and the elderly compared with before,” she said. “For people who are fully vaccinated, including with a bivalent vaccine, and with ready access to treatments such as remdesivir, Paxlovid, and other additional treatments, we are seeing overall much better outcomes now compared to where we were, say, a year or previously.”

Kotton seemed uncertain of the value of authorizing a spring booster.

“We don’t want to just give doses because people are nervous, right? We want to make sure that there is a good reason based on data that we would want to give additional doses of vaccine,” she said. “So we’re basically waiting — waiting to hear more from the CDC and FDA.”

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