FDA advisers debate how to update COVID-19 vaccines

A group of Food and Drug Administration advisers agreed on Wednesday that COVID-19 vaccines will likely need to be updated to keep pace with a rapidly evolving coronavirus, but said they would need more information. to guide future decisions.

The FDA convened the panel, made up of independent vaccine and public health experts, to advise on how drugmakers should tailor their vaccines to better guard against variants like omicron or others. that may emerge over time.

The matter is urgent because about half of American adults who have received a two-dose series of vaccines have yet to receive a third dose, which has restored some protection and increased antibody levels. falling. The FDA cleared booster doses for all adults in November and last month cleared a fourth dose for the elderly and immunocompromised.

“As the fall season approaches, only half of the global population has received a third dose,” meaning the other half won’t have lasting protection, said bureau chief Peter Marks. from the FDA that reviews vaccines, at Wednesday’s meeting.

“That’s a lot of vaccines,” he added. “Do you change the composition of your vaccine so that when you boost these people, you give them the best chance of having longer-lasting protection?”

The experts on the panel attempted to answer this question, but struggled to determine the best composition and assess whether it remained safe and effective enough for wide use.

“We’re up against a conundrum here,” said Ofer Levy, a physician and director of an immunization program at Boston Children’s Hospital. “It’s going to be difficult to generate all the data we want in a short time when a new variant emerges.”

Many advisers say the best data to base decisions on is what’s called a “correlate of protection,” or a defined level of immune response that establishes whether a person is protected against disease or infection. So far, this information has been hard to come by, although researchers are trying.

Without an established immunity threshold, the FDA and other health agencies have had to rely on comparing antibody levels after vaccination, a process Marks called a “correlate of poor person immune protection.” .

When debating COVID vaccine changes, FDA officials and agency advisers drew parallels to the system the United States and other countries use to update flu shots each year. The process usually begins in February or March with the selection of strains that should be circulating the following winter, and allows drugmakers to manufacture enough doses for fall vaccination campaigns.

Likewise, while US health agencies hope to have updated COVID vaccines ready by fall, clinical trials testing those vaccines will likely need to begin next month for drugmakers to report results and get new ones made. new doses on time, a government official told the committee.

“If you are not on your way to this clinical trial in early May, I think it will be very difficult to have, collectively among manufacturers, enough products to meet this demand,” said Robert Johnson, assistant secretary. deputy for the US Biomedical Advanced Research and Development Authority, or BARDA.

Both Pfizer and Moderna are testing omicron-tailored versions of their vaccines, and Moderna is also investigating a “bivalent” formulation that targets omicron and the original strain of coronavirus.

Although the Advisory Committee did not vote on specific proposals, it decided to reconvene on the matter and some members suggested that it take a more active role in guiding the update process.

“I feel like on some level, corporations are dictating the conversation here,” said Paul Offit, director of the vaccine education center at Children’s Hospital of Philadelphia. “It really has to come from us.”

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