The FDA would like companies to submit clinical data showing that the modified version of their vaccine is more effective against new variants than their original vaccine. The agency is also asking vaccine makers to test their modified vaccines in people who have never been vaccinated and in people who were previously vaccinated.
Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said trials to test the immune response prompted by a tweaked vaccine would probably involve a few hundred individuals, and might take about two or three months.
Compare that with a typical Phase 3 clinical trial, which can involve tens of thousands of patients and can take several months longer.
Such a speedy vaccine alteration is the norm for viruses like influenza, said Dr. Diane E. Griffin, a viral immunologist at the Johns Hopkins Bloomberg School of Public Health.
It’s possible that in the future, modified vaccines could be authorized without the need for additional clinical studies, the FDA noted. But that is not yet the case.
The agency emphasized that the two vaccines currently authorized for use in the U.S. — the one made by Pfizer and BioNTech and another developed by Moderna and the National Institutes of Health — are still effective against the mix of variants now circulating in the U.S.
That said, “it’s reasonable to think these companies are thinking about these changes or are thinking they may need to make changes,” Griffin said. “This just helps them to know what kind of information the FDA would want and what they wouldn’t need.”
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