Companies need several months to manufacture a new vaccine, so the deadline for choosing a vaccine formula ready for deployment in October has arrived. The FDA is expected to issue a final decision in the coming days.
Coronavirus vaccine tracking
But no one knows which variants will be circulating this winter, and it’s reasonable to expect that any omicron variant incorporated into the updated vaccine will be in the rearview mirror by the time the shots come in the guns. Updated vaccines that include BA.1 have been tested in humans for months, but this variant has been circulating this winter and has already been eclipsed by other versions of omicron; the BA.4 and BA.5 subvariants already account for half of the cases in the United States.
There is also uncertainty about whether updated vaccines will really protect people better. The companies have shown they are able to trigger slightly higher levels of virus-blocking antibodies, but it’s still unclear whether this will translate into better protection against hospitalization or infection. The hope is that a revamped vaccine will broaden the immune response.
“We’re being asked, more or less, to have a crystal ball today,” said Arnold Monto, acting chairman of the FDA’s advisory board and professor emeritus of public health at the College of Public Health. University of Michigan.
During the discussion, many committee members said the vaccine should be a multi-strain vaccine that includes the original version of the virus and a component of omicron. Many FDA members and officials favored the BA.4 and BA.5 omicron subvariants, but some saw promise to include the BA.1 version of omicron.
“I think that given the speed of evolution [of the virus] we’re going to be behind the eight ball if we wait any longer,” said Mark Sawyer, professor of clinical pediatrics at the University of California San Diego School of Medicine. “The public perception is that the FDA is already delaying approvals. I think we have enough data here presented today to move forward with a strain change.
Vaccine companies including Moderna, Novavax, Pfizer and its German partner BioNTech have presented sometimes conflicting data on potential booster strategies, leaving committee members to triangulate between overlapping, sometimes divergent results.
Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia, called the data “uncomfortably sparse” and voted against the strain change. He wondered if the modest difference in how the modified vaccines elicited an immune response was a big enough difference to translate into a benefit for people.
“I don’t think it’s fair to ask people to take a risk…if we don’t feel comfortable with the level of protection we’re likely to get,” Offit said.
The companies each presented data to support their preferred strategy.
Moderna, for example, favors a bivalent vaccine designed to protect against the original version of the virus and the omicron BA.1 variant. The company said it could start delivering the vaccine this summer, but warned that a vaccine including BA.4 and BA.5 could take until late October or early November.
Pfizer and its German partner BioNTech, however, found that a vaccine targeting a single variant of the virus, BA.1, was better than a bivalent formulation. The company also presented mouse data suggesting that a vaccine designed to combat the omicron subvariants expected to soon dominate in the United States, BA.4 and BA.5, could elicit stronger immune responses. strong and larger. The company is said to be ready to supply either version of the vaccine by the first week of October.
Novavax’s vaccine has not yet been licensed in the United States, but uses a different technology – delivering a lab-brewed viral protein. The company presented data suggesting that additional doses of its existing vaccine could be protective, even against omicron subvariants. Clinical trials of its omicron booster are ongoing, with results expected in September.
Adam Berger, director of the division of clinical research and health care policy at the National Institutes of Health, said the data presented at the meeting suggests that while a universal vaccine switch recommendation is preferred for reasons of simplicity, the range of results suggests “there isn’t a single answer for whether a strain change is necessary.
Several experts have expressed concern that if the United States changes the composition of its vaccines, it could exacerbate global vaccine equity issues and vaccine perceptions. It was also unclear whether a vaccine change would apply to adults or also include children. Several experts have said that if the vaccine is changed for children, they would like to see more testing.
But during the public comment session, several parents made a passionate plea for vaccines to be updated for all age groups, including the youngest children.
The wait for vaccines for children under 5 has been “long and excruciating”, said mother-of-three Kate Schenk. “We cannot let this happen again. Children must be eligible to receive these updated boosters alongside older cohorts – without being left behind, without protection.
What to know about the coronavirus vaccine for children under 5
Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, pointed out that half of Americans have not received a booster shot, despite clear evidence that a third vaccine replenishes and expands protection. Even those who received boosters will become vulnerable again over time as immunity wanes.
“The better the match of the vaccines to the circulating strain, we believe this may correlate with better vaccine efficacy and potentially better durability of protection,” Marks said.
But even an updated vaccine won’t reset the pandemic or offer perfect protection against a rapidly evolving and highly transmissible virus. The omicron subvariants already increasing in frequency today are unlikely to be the ones the world faces in the fall. How vaccines based on them will protect against future iterations of the virus will not be fully known until they are used.
The process has been compared to picking up the flu shot every year. Some years it is a better match to circulating flu strains than others.
But influenza is a different virus, and the meeting is a first step in the long-term challenge of trying to devise a vaccination strategy.
“I remind you that the parallel route of influenza strain selection, which works very well, was a process that was refined over many, many years. And so we probably have quite a bit of work to do,” said Jerry Weir, director of the Division of Viral Products in the Office of Vaccine Research and Review. “It’s a different virus. We have a lot of work to do on the strain selection process for covid vaccines.
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