A federal advisory panel on June 28 recommended updating COVID-19 booster vaccines in the United States to include an Omicron component, while urging the need for more information on how well these shots work on emerging strains of the virus.
The Vaccines and Related Biological Products Advisory Committee of the Food and Drug Administration voted 19-2 in favor of a new formulation – although what that formulation will be is yet to be determined. The FDA often incorporates the views of its advisers into its decisions, although it is not bound to do so.
In this case, though, top FDA staff at the meeting seemed inclined to encourage the development of COVID vaccines modified to keep up with an evolving virus. Two Omicron subvariants, BA.4 and BA.5, which first appeared in South Africa in March 2022, have spread to the United States and have begun to increase rapidly in proportion to the virus population, the FDA said in a briefing for the meeting.
New information from the Centers for Disease Control and Prevention shows the two highly infectious subvariants now make up more than half the number of new COVID cases in the US.
Double-duty vaccine
In summarizing the message of the advisory committee, Peter W. Marks, MD, PhD, the director of the FDA’s Center for Biologics Evaluation & Research, said panelists had lent support to modifying vaccines to protect against both the original, or “ancestral” viral strain, and against Omicron, perhaps emphasizing the newly emerging subvariants.
Dr. Marks emphasized that this is a challenging decision, as no one has a “crystal ball” to forecast how SARS-CoV-2 will evolve.
“We are trying to use every last ounce of what we can from predictive modeling and from the data that we have that’s emerging, to try to get ahead of a virus that has been very crafty,” he said.”It’s pretty darn crafty.”
Limited data
Voting “no” were Paul Offit, MD, of Children’s Hospital of Philadelphia and Henry Bernstein, DO, MHCM, of Hofstra/Northwell Health in New Hyde Park, N.Y.
Both Dr. Offit and Dr. Bernstein earlier in the meeting expressed doubts about the evidence gathered to date in favor of a strain change. Dr. Offit had noted that protection seems to persist from the vaccines now available.
“To date, the current prototypical vaccines, the ancestral strain vaccines do protect against serious illness,” he said. “We don’t yet have a variant that is resistant to protection against serious illness.“
Dr. Bernstein said he was “struggling” with the question as well, given the limited data gathered to date about the vaccines and emerging strains of the virus.
Other panelists also expressed reservations, while supporting the concept of altering vaccines to teach the body to fight the emerging strains as well as the original one.
Panelist Wayne Marasco, MD, PhD, of Harvard Medical School, Boston, who voted yes, noted the difficulties of keeping up with the rapidly evolving virus, saying it’s possible that Omicron strains BA.4 and BA.5 could peak within months. That could be before the vaccines are even distributed – if all goes to plan – in the fall.
“This is a step in the right direction, but we have to reevaluate this as we move forward,” Dr. Marasco said, adding that a good strategy would be to elicit antibody response to bridge more than one variant of the virus.
Even panelists like Dr. Marasco who voted yes stressed the need for further data collection about how vaccines may be adapted to a changing virus. But they also acknowledged a need to give vaccine makers a clear indication of what the medical community expects in terms of changes to these shots.
“With the waning vaccine efficacy and the confluence of risk this fall, we need to make a move sooner rather than later and direct our sponsors in the proper direction,” said FDA panelist Michael Nelson, MD, PhD, of the University of Virginia, Charlottesville, said before the vote.
A version of this article first appeared on Medscape.com.