Advisers to FDA weigh in on updated COVID boosters for the fall
In a daylong virtual meeting, a panel of experts advising the Food and Drug Administration came out in general support of efforts to develop new COVID-19 vaccines tailored to variants.
The committee wasn't asked to vote on any specific recommendations to the agency but instead discussed the framework for making decisions about when to change the viral strain or strains used for future vaccines, including boosters.
"I think we're in uncharted territory because with SARS-CoV-2 a lot of things have happened that have never happened before," said Dr. Arnold Monto, professor emeritus at the University of Michigan and acting chair of the committee.
It's likely the panel will reconvene in May or June to consider a more specific proposal for reformulation of COVID-19 vaccines.
The process used to tweak annual flu vaccines to match circulating strains is one model that may inform the process for COVID-19, but there are still many unknowns about how the coronavirus may change and stark differences between the influenza virus and SARS-CoV-2.
Fall target for new kind of booster
The critical consideration is whether a variant-specific booster should be made available this fall. The rise of the omicron variant, and lately a subvariant called BA.2, has sharpened the question. The vaccines now in use in the U.S. are based on the form of the virus that circulated at the beginning of the pandemic and are less effective against some later strains.
"Although we've seen a major decline in the number of COVID-19 cases in the country, the virus continues to circulate and it will continue to do so and will potentially cause waves of an increased numbers of cases," said Dr. Peter Marks, head of the FDA's Center for Biologics Evaluation and Research, at the start of the meeting. "This is of particularly concern as we head into the fall and winter season."
Marks also noted that the coronavirus will have had another more time to evolve by the time fall arrives in the U.S.
During the morning session, Israeli researchers presented data on the waning protection of a single booster dose of the Pfizer-BioNTech vaccine and the increased protection of a second booster against infections, which was fleeting, and severe illness, which was longer lasting. The rapid spread of the omicron variant contributed to the decline in protection from immunization with one booster.
Israeli authorities approved a second booster in early January for people 60 and older and others at high risk or who worked in health care. The Israeli experience contributed to the FDA's decision in late March to authorize a second booster dose for people 50 and older as well as for other people with compromised immune systems.
Predicting viral evolution is 'quite difficult'
Rapid genetic changes in the coronavirus are driving its ability to evade the immune response from vaccination and prior infections. The continuing changes complicate decisions about which strains to include in new vaccines.
"In general, from everything we've seen, we should expect a lot of evolution going forward, and we should have methods to keep up with this evolution in terms of our vaccination platforms," said Trevor Bedford, who studies viral evolution at the Fred Hutchinson Cancer Center in Seattle.
He said that predicting where the virus is headed is "quite difficult." The coronavirus has been evolving must faster than the flu. Significant new variants of the coronavirus have emerged in just months instead of the years it can takes for the flu to make such jumps.
Based on the rate of the coronavirus' evolution so far and uncertainty about what lies ahead, Bedford estimates a dangerous new variant like omicron could emerge within about a year and a half or maybe not for more than a decade.
There isn't much time to make vaccine changes in time for an immunization push this fall. "If you're not on your way to a clinical trial by the beginning of May, I think it's going to be very difficult to have enough product across manufacturers to meet demand," said Robert Johnson, deputy assistant secretary of the federal Biomedical Advanced Research and Development Authority.
FDA's Marks acknowledged that there is a compressed timetable for deciding upon booster makeup, but there may be "some wiggle room" that could allow for a determination in May or June.
There's a lot riding on the decision. "We simply can't be boosting people as frequently as we are," Marks said, adding that the second booster dose authorized recently by FDA was "a stopgap measure" to help protect the most vulnerable people.
The goal for a reformulated booster sometime later this year, Marks said, would be to "boost again in order to protect against a wave that could come at the time we're at highest risk."
In closing remarks, committee chair Monto said, "We'd love to see an annual vaccination similar to influenza but realize that the evolution of the virus will dictate how we'll respond."
Rob Stein contributed to this report. Copyright 2022 NPR. To see more, visit https://www.npr.org.
AILSA CHANG, HOST:
The federal government today launched efforts to plan yet another possible COVID-19 vaccine campaign for the fall in order to protect people against yet another possible surge next winter. NPR health correspondent Rob Stein joins us now with more details. Hi, Rob.
ROB STEIN, BYLINE: Hey there.
CHANG: So explain what exactly happened today.
STEIN: The Food and Drug Administration convened a special meeting of independent scientific advisers to try to figure out what should happen next with the vaccines, which is a really tough but obviously extremely important question. Here's how FDA's Dr. Peter Marks set the stage for the day-long virtual meeting today.
(SOUNDBITE OF ARCHIVED RECORDING)
PETER MARKS: Although we've seen a major decline in the number of COVID-19 cases in the country, the virus continues to circulate, and it will continue to do so and will potentially cause waves of an increased number of cases. This is particularly of concern as we head into the coming fall and winter season.
STEIN: So the advisers heard detailed presentations from the CDC and FDA, as well as outside scientists, about the trajectory of the pandemic, the evolution of the virus and the effectiveness of the vaccines.
CHANG: OK. So what did they hear in these presentations?
STEIN: Yeah. So researchers at the University of Washington told the committee that another surge is probably likely next winter because, you know, immunity people have from the vaccines and having already caught the virus will probably have faded even more by then. And the cold weather will be driving people back indoors where the virus spreads more easily.
At the same time, Trevor Bedford at the Fred Hutchinson Cancer Center told the advisers that the virus has been evolving incredibly fast, with new variants emerging in just months instead of years it takes for the flu to evolve. And another dangerous new variant like omicron could easily emerge, perhaps within a year or so, but maybe for not more than a decade. But he says we have to be ready.
(SOUNDBITE OF ARCHIVED RECORDING)
TREVOR BEDFORD: We really don't know whether these wildly divergent viruses will be a common feature or a rare feature of endemic SARS-CoV-2 evolution. But in general, from everything we've seen, we should expect a lot of evolution going forward, and we should have methods to keep up with this evolution in terms of our vaccination platforms.
STEIN: The committee also heard about the possible option for the next round of shots. The most likely is a new version of the vaccine - you know, like one that switches things up to specifically target the omicron variant or maybe one that combines omicron with another variant like beta or delta or the original strain to hopefully provide more protection against any new variants that might evolve.
CHANG: Wow. OK. So did the committee recommend anything today?
STEIN: You know, the committee didn't make any specific recommendations today. Instead, they kind of struggled with how best to make this crucial decision with so many unknowns. You know, how will they judge whether another round of shots is definitely necessary? And if so, how will they judge new versions of the vaccine to decide which one to pick, especially when no one knows which variant might be dominant by then? Here's Dr. Haley Altman Gans from Stanford University.
(SOUNDBITE OF ARCHIVED RECORDING)
HALEY ALTMAN GANS: What we're all grappling with is that this is an unsettled environment in which we're trying to move forward.
STEIN: And, you know, in the end, the experts will have to make the best educated guess possible about which strain or strains make the most sense - you know, like we do with a flu vaccine every year - and hope it's right. But that's tough because this virus has been so unpredictable and evolving so fast.
They also discussed whether the fall shots would be the beginning of an annual vaccine campaign like the flu. And the answer appears to be maybe, but maybe not. We'll just have to wait and see how long our immunity holds up and what the virus does next.
CHANG: Oh, my God, Rob - so many open questions. So what happens next at this point, real quick?
STEIN: Yeah. The FDA will bring these advisers back, probably in May or June, to make some specific recommendations so the vaccine companies have enough time to make enough vaccines for another campaign by the fall.
CHANG: That is NPR health correspondent Rob Stein. Thank you, Rob.
STEIN: Sure thing. Transcript provided by NPR, Copyright NPR.