knowledge

When Americans line up for flu vaccines next fall, they will almost certainly be getting vaccines that no longer contain protection against a family of flu viruses that appears to be extinct.

Experts who advise the Food and Drug Administration on vaccine-related issues voted unanimously on Tuesday to recommend that the FDA approve trivalent flu vaccines for the 2024-2025 season, instead of the quadrivalent, or four-in-one, shots that have been the industry standard for the past decade or so.

advertisement

The Vaccines and Related Biological Products Advisory Committee — VRBPAC, as it’s known — has been pushing for the removal of one of the influenza B components in flu vaccines, the portion that targeted B/Yamagata viruses, for some time now. B/Yamagata viruses haven’t been detected anywhere in the world since late March 2020, when Covid pandemic lockdowns and social distancing appeared to have halted circulation of this family of lineage of flu B.

Last fall, the World Health Organization’s vaccine advisers agreed, recommending that the B/Yamagata component be removed from future iterations of flu vaccines. And when VRBPAC met in early October to vote on the strains that should go into flu vaccines made in this country for the Southern Hemisphere 2024 winter, members of the committee pressed an industry representative attending the meeting on behalf of the manufacturers to ensure that the transition from a quadrivalent back to a trivalent formulation be completed in time for the 2024-2025 flu vaccine campaign.

Sign up for Morning Rounds

Understand how science, health policy, and medicine shape the world every day

The representative, David Greenberg, Sanofi’s interim vaccines medical head for North America, argued that the industry needed more time, because regulatory agencies in a number of countries were not yet ready to handle the transition. The manufacturers were hoping for a synchronized global switch, one that would start with the Northern Hemisphere flu vaccines for 2025-2026. But VRBPAC and the FDA were unwilling to put off the change for that long.

advertisement

On Tuesday, Greenberg told VRBPAC all the manufacturers who supply the U.S. market will make trivalent vaccines for this country.

The meetings votes were to accept the WHO’s recommendations for strains to be included in the winter 2024-2025 shots. The WHO made recommendations for both trivalent and quadrivalent vaccines but VRBPAC only voted to recommend trivalent vaccines for the U.S. market.

“For the upcoming Northern Hemisphere 2024-25 flu season, we will follow VRBPAC’s recommendation and will distribute [trivalent vaccine] in the United States,” a Sanofi spokesperson said in an email after the meeting concluded. “For the European region, we … anticipate the move to [trivalent] for the 2025-26 Northern hemisphere season due to the more complex regulatory situation. For all other countries, transition will happen on a country to country basis, in accordance with national regulations.”

Jerry Weir, director of viral products in the FDA’s Center for Biologics Evaluation and Research, acknowledged making the shift has been easier in the U.S. than elsewhere, because all the manufacturers who supply flu vaccine to this market had existing trivalent vaccine licenses that could be reactivated.

Related: CDC eases isolation guidance for Covid and other respiratory illnesses

During his presentation, Greenberg cautioned the committee that uptake of flu vaccine has declined in the wake of the Covid-19 pandemic and he noted that the industry is worried that the move to take B/Yamagata out of the vaccine could be misread by an increasingly vaccine-hesitant public.

While several committee members agreed that there needs to be careful messaging surrounding the move, VRBPAC chair Hana El Sahly, a professor of molecular virology and microbiology at Baylor College of Medicine, argued that the shift could be used to bolster confidence in vaccines and in the regulatory process that approves them.

“We don’t want to vaccinate you for a virus that’s no longer in circulation for three, four years now,” she said, adding the decision “may play out positively in that the public health officials and the regulators and their advisers are following closely the [epidemiology] and acting accordingly.”