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CDC panel mulls changes to RSV vaccine recommendation

Advisers to the Centers for Disease Control and Prevention are weighing updates to their recommendation older adults get vaccinated for respiratory syncytial virus, discussing changes at a meeting Thursday that would more forcefully encourage some individuals receive a shot.

At the meeting, the Advisory Committee on Immunization Practices reviewed safety and efficacy data on RSV vaccines sold by GSK and Pfizer, as well as clinical trial data for an experimental shot from Moderna that’s nearing market.

Currently, the CDC recommends adults 60 years or older discuss RSV vaccination with their physician — a process known as “shared clinical decisionmaking.” Advisers debated whether, for some individuals at higher risk, a universal recommendation would be more appropriate. They wanted more data before making a decision, however, likely at a follow-up meeting scheduled for June 26 to June 28.

The two approved vaccines from GSK and Pfizer, respectively sold as Arexvy and Abrysvo, hit the market last year for older adults. Both have sold well, but GSK’s has claimed about two-thirds of the U.S market.

Moderna aims to compete as well, and CDC advisers reviewed data from a Phase 3 trial of the company’s RSV shot. The results showed the vaccine, dubbed mRNA-1345, was initially 84% effective in preventing RSV-related disease with two or more symptoms in adults 60 years or older. That efficacy appears to wane somewhat over time, as updated data show a 63% efficacy rate over a longer time period.

Additionally, on Thursday, Pfizer released updated data on Abrysvo’s effectiveness, saying the shot was 78% effective through a second season in older adults. Pfizer’s disease definition was slightly different than Moderna’s however, measuring the vaccine’s prevention of disease with three or more symptoms.

Moderna has submitted its vaccine for Food and Drug Administration approval, which is set to decide by mid-May. If approved, ACIP could recommend its use in June, Jefferies analyst Michael Yee wrote in a note to clients. But whether the ACIP recommends an annual or biennial vaccination routine “might present risk for use of [Moderna], as GSK has suggested higher durability,” Yee added.

CDC advisers also discussed Thursday the risk of severe adverse events to the current vaccines from GSK and Pfizer.

In particular, committee experts discussed Guillain-Barré syndrome, or GBS, an uncommon neurological condition that can cause muscle weakness and, in very rare instances, paralysis. In testing of their respective vaccines, GSK reported one case of GBS while Pfizer reported two.

Out of the roughly 9.6 million RSV vaccine doses administered to date, there were 23 verified cases of GBS reported to a federal adverse event database, 15 with Abrysvo and 8 with Arexvy. In most of those cases, however, recipients also received another vaccine, such as for influenza, which can complicate analysis of the side effect’s cause.

While CDC analysts found the data suggestive of a slight increase in GBS risk following RSV vaccination in older adults, they couldn’t confirm a link. They also noted that any possible risk must be put in the context of the vaccine’s benefit.

Amadea Bitton, a physician and ACIP panelist, said the benefits of vaccination against RSV still outweigh possible risks.

Advisers also discussed the timing of vaccination and judged that shots in the late summer or early fall ahead of the typical RSV season would have the largest benefit.