The rollout of updated Covid vaccines for healthy children and adults this fall is likely to be delayed after the Food and Drug Administration suggested Tuesday that it will require another clinical trial before signing off on the shots.
In a paper published in the New England Journal of Medicine, FDA Commissioner Dr. Marty Mak and Dr. Vinay Prasad, the FDA’s new vaccine chief, wrote that any new Covid vaccine now must undergo placebo-controlled clinical trials — meaning, some people would get the actual vaccine while others get an inactive substance like a saline shot, to compare results.
The requirement isn’t expected to affect the rollout for older adults and other groups at high risk for severe illness, as drugmakers are exempt from additional testing for those groups.
Previously, updated Covid vaccines had been cleared by the FDA similar to flu vaccines.
The original Covid shots, from Pfizer and Moderna, approved in late 2020, went through placebo-controlled trials. Then, the drugmakers transitioned to smaller studies to test how well the updated shots triggered an immune response against the current variants circulating in the U.S.
Mak and Prasad on Tuesday questioned whether that should be the standard practice moving forward, noting that only a quarter of people in the U.S. get the updated shots each year, including less than a third of health care workers.
In comparison, about 75% of health care workers get seasonal flu shots, according to data from the Centers for Disease Control and Prevention.
The Covid shot policy, the officials wrote, “has sometimes been justified by arguing that the American people are not sophisticated enough to understand age- and risk-based recommendations.”
“We reject this view,” they added.
Who will be able to get the Covid shots?
Under the FDA’s new guidance, the drugmakers will need to run new trials that track participants for at least six months.
The main goal of the trials should be showing that the shots help prevent symptomatic Covid, the officials wrote, with data showing at least 30% effectiveness. People who’ve had Covid in the past should still be included in the trial to better reflect the general population, they said.
Drugmakers can still use smaller studies, known as immunogenicity studies, to get approval for adults 65 and up, as well as children and adults with at least one medical condition that puts them at higher risk for Covid.
The FDA said many people are considered at high risk, including pregnant women and those with obesity or who have mental health conditions such as depression. Other conditions linked to severe Covid illness include diabetes, heart disease and asthma.
“Ultimately, these studies alone can provide reassurance that the American repeat-boosters-in-perpetuity strategy is evidence-based,” the officials wrote.
Estimates, they said, suggest that 100 million to 200 million Americans will have access to the updated vaccines.
The FDA’s mandate comes ahead of Thursday’s vaccine advisory committee meeting, where outside experts will discuss which strains should be included in the next round of Covid shots.
In briefing documents published earlier Tuesday, FDA staff wrote that updating the vaccines to more closely match currently circulating strains may “provide added benefit” in anticipation of an uptick in cases during the fall and winter.
The change means it will be near impossible for Pfizer and Moderna to complete the new trials in time for the fall season. Aside from running the trials, the drugmakers will still need to design the trials and enroll participants, which can also take several weeks or months.
It’s also unclear what the change will mean for healthy children and adults who want to get the updated shots.
Dr. Paul Offit, the director of the Vaccine Education Center at Children’s Hospital of Philadelphia and a member of the FDA’s vaccine advisory committee, said people considered at “low risk” can still be harmed by the virus.
“Low risk doesn’t mean no risk,” he said. “I mean anybody can be hospitalized and killed by the virus.”
Kennedy’s influence on vaccine rules
A change to the way Covid vaccines are updated was expected. Earlier this month, Health and Human Services Secret Robert F. Kennedy Jr. mandated that all new vaccines must undergo placebo-controlled clinical trials.
Until Tuesday, it wasn’t clear whether HHS considered Pfizer’s and Moderna’s updated shots “new vaccines,” requiring new clinical trials.
Former government health officials feared that the FDA, under Kennedy, was moving to slow-walk vaccine approvals.
Over the weekend, the FDA approved Novovax’s vaccine after weeks of delay. In an unexpected turn, however, the agency limited the use of the shot to people 65 and up and teens and adults with at least one medical condition that puts them at risk of severe illness. Typically, it’s the CDC that makes recommendations about who should get the vaccines.
Mak had warned about changes to the way vaccines are tested and approved, saying last week that the agency would soon “unleash a massive framework.”
Kennedy has long opposed vaccines, including the Covid shot.
In 2021, he submitted a citizens’ petition requesting that the FDA revoke the authorization of the Covid vaccines.
The same year, he called the Covid shots “the deadliest vaccine ever made,” citing rare cases of myocarditis in young men. Studies find that the risk of myocarditis is higher — and typically more severe — in people with a Covid infection than after the vaccine.
Last week, at a Senate Health, Education, Labor and Pensions Committee hearing, Kennedy also falsely claimed that the only vaccines tested against a placebo were the Covid shots.
The move prompted Committee Chair Bill Cassidy, R-La., to later paused the hearing to correct the health secret.
“For the record, that’s not true. Rotavirus, measles and HPV vaccines have been [evaluated against a placebo] and some vaccines are tested against previous versions. So just for the record, to set that straight,” Cassidy said.
Kennedy isn’t the only health official who has been critical of the Covid vaccines. Mak, Prasad, Dr. Tracy Beth Hoeg, a special advisor to Mak, and Dr. Jay Bhattacha, the head of the National Institutes of Health, have as well.
