(CN) — Nineteen out of 21 members on a Food and Drug Administration advisory panel voted Tuesday in favor of recommending the inclusion of an omicron component for Covid-19 booster vaccines this fall.
While administration of these vaccines is not yet fully authorized by the FDA, the Vaccines and Related Biological Products Advisory Committee's recommendation is part of an effort to avoid another huge Covid-19 outbreak during the upcoming colder seasons.
"Our goal today is to try to address a situation that we are concerned about in the fall. We have a situation where roughly half of Americans have only received two vaccines to protect them against Covid-19, and for the other half that has received a booster, all of those individuals will have waning immunity as we move into the fall months," said Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research.
The committee consisting of expert doctors discussed data presented by the Centers for Disease Control and Prevention, World Health Organization, Center for Biologics Evaluation and Research and vaccine manufacturers Novavax, Moderna, Pfizer and BioNTech.
The data showed that currently circulating coronaviruses are "antigenically distinct" from strains that circulated early in the pandemic and on which current Covid-19 vaccines are based.
While the vaccines currently in use still confer high levels of protection against severe disease outcomes for all variants, the data suggests a booster aimed at targeting the rapidly evolving omicron variant is needed.
Omicron is the latest and most transmissible Covid-19 variant to date. It has become dominant globally, poses a higher risk of reinfection than previous virus strains and continues to evolve into subvariants that are also antigenically distinct.
Results from observational studies have shown by several measures, including escape from antibody neutralization and protection against infection, the current vaccines appear less effective against omicron variants than against previous strains of the virus.
Although the available data is still very limited, committee members agreed that it indicates an omicron-targeted booster vaccination will increase and broaden the antibody response to the variants.
"We are behind, so considering these questions now before there is a need is actually very important. So, we can't always wait for the data to catch up," said Dr. Hayley Altman-Gans, a professor of pediatrics at Stanford University Medical Center.
As of last week, there have been 1.01 million confirmed Covid-19 deaths in the U.S., with 46% attributed to all variants, 27% to delta, and 12% to Omicron, according to the CDC's Epidemiology Task Force.
Even after the emergence of omicron, unvaccinated people were found to be 3.5 times more likely to face hospitalization.
Although a majority of the committee voted in favor of the need for a new booster, many members still expressed safety concerns.
"If we get to the point of administering too many boosters, I worry that we could begin to see some untoward side effects and in particular in children," said Dr. Cody Meissner, director of pediatric infectious diseases at Tufts University School of Medicine. "I think that it should probably be directed initially at adults rather than children while we work out the dosages and potential side effects."
Clinical studies for the mRNA Covid-19 vaccines made by Moderna and Pfizer/BioNTech showed significantly higher binding antibodies against omicron variants when administered as a fourth dose (second booster) in previously uninfected adults.
The mRNA vaccines introduce the genetic recipe for the Covid spike protein into our cells, and then our own cells make the protein to which our immune system responds.
Novavax's protein-based vaccine also showed success in broadly cross-neutralizing antibodies across prototype and emerging variants following booster doses.
Earlier this month, the FDA panel recommended nearly unanimously that the agency grant an emergency authorization to the Novavax Covid shot, but authorization has been delayed due to complexities involved with the manufacturing process.
Novavax would be the first protein-based Covid-19 vaccine in the U.S., similar to other approved vaccines for shingles, hepatitis B and influenza.
"I think we need to have better central coordination not just for those studies but what the plan is going forward," said Dr. Bruce Gellin, chief of global public health strategy at the Rockefeller Foundation. "Without such a plan, we're going to be playing whack-a-mole as this virus evolves because it will continue to evolve and we will get better at it but we still need to get ahead of it."
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