Pfizer gets a leg up in RSV as FDA clears jab for all adults

A new FDA approval has given Pfizer a broader label for its respiratory syncytial virus (RSV) vaccine Abrysvo than rival shots from GSK and Moderna, but it may not make much of a difference in the battle for market share.

The US regulator has cleared Abrysvo for use in adults aged 18 to 59 at risk of RSV-related disease, extending its earlier label, which covered the 60 and over age bracket.

GSK's market-leading Arexvy shot is currently indicated for people aged 50 and over, while recent entrant mResvia from Moderna can be used in the over-60s only at the moment.

Abrysvo has far and away the broadest indications among any of the three vaccines, as it is also the only one to be approved for use in pregnancy to protect infants from birth up to six months of age.

The issue facing Pfizer, GSK, and Moderna, however, is that the US government has been rolling back its recommendations for RSV immunisation to include older people, rather than younger populations.

Last year, the US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunisation Practices (ACIP) recommended RSV shots for all adults aged 60 and over. For the coming season, however, it has amended that advice to cover all people aged 75 and older, with those in the 60 to 74 range only eligible if they are at increased risk for severe disease.

The move followed concerns raised earlier this year that RSV vaccination may be linked to an elevated risk of a rare side effect called Guillain-Barré syndrome (GBS), a rare disorder that causes muscle weakness and sometimes paralysis. A few cases have been reported in the Arexvy and Abrysvo clinical trials, but none in the mResvia studies.

Meanwhile, the CDC's advice is if they received an RSV vaccine last year, people will not need another shot this year.

Sales of all three FDA-approved vaccines in the 2024-25 season will be scrutinised to gauge the impact of that new advice. Last year, Arexvy came out on top in the market tussle with sales of $1.6 billion in sales last year, compared to $890 million for Abrysvo. mResvia wasn't approved until May this year.

In a statement, Pfizer's chief commercial officer said that RSV "represents a significant threat to younger adults with certain chronic conditions."

The company cited CDC and other data suggesting that, among US adults aged 18 to 49 years, 9.5% have an underlying chronic condition, such as obesity, diabetes, chronic obstructive pulmonary disease (COPD), heart failure, chronic kidney disease, and asthma that puts them at increased risk of lower respiratory tract infections caused by RSV. That rises to almost a quarter (24.3%) of the 50 to 64 group.