USA – The U.S. Food and Drug Administration (FDA) has granted approval for Pfizer’s respiratory syncytial virus (RSV) vaccine, Abrysvo, for adults aged 18 to 59 who are at an increased risk of developing lower respiratory tract disease (LRTD).
This landmark approval marks the first RSV vaccine available for adults younger than 50, potentially reshaping the landscape of RSV prevention.
The approval of Abrysvo positions Pfizer ahead of its competitor, GSK, whose RSV vaccine Arexvy is approved for individuals aged 50 and older.
However, the true impact of this approval remains uncertain until the Centers for Disease Control and Prevention (CDC) issues guidelines for its use across the broader age range.
In addition to Pfizer’s Abrysvo and GSK’s Arexvy, Moderna has recently entered the RSV adult vaccine market with its product, mRESVIA, which received FDA approval five months ago.
Recently, the CDC revised its recommendations for RSV vaccines, now focusing on adults aged 75 and older and those aged 60 to 74 who are at higher risk for severe illness. This update narrows the earlier guidance, which applied to all adults aged 60 and above.
The change was prompted by concerns about a potential link between RSV vaccination and a rare side effect known as Guillain-Barré syndrome (GBS), a condition that leads to muscle weakness and sometimes paralysis.
A few cases of GBS were observed in the clinical trials for Arexvy and Abrysvo, but none were reported in the studies for mResvia.
Recent approvals and ongoing trials
The FDA’s endorsement of Abrysvo comes after its initial approval in May 2023 for adults aged 60 and older.
The vaccine was also authorized for pregnant women between 32 and 36 weeks of gestation to protect their infants from RSV.
The latest approval was supported by the phase 3 MONeT trial, which demonstrated that Abrysvo produced a non-inferior immune response in adults aged 18 to 59 compared to older adults.
The MONeT trial included 681 adults with chronic medical conditions and an additional 200 immunocompromised individuals.
Results indicated that participants in substudy A received a single dose of Abrysvo, while those in substudy B received two doses.
Addressing a significant health concern
“RSV represents a significant threat to younger adults with certain chronic conditions.
After decades of vaccine research by the scientific community and Pfizer, we now have the opportunity to help alleviate the burden of RSV in this high-risk adult population,” said Aamir Malik, Pfizer’s chief U.S. commercial officer.
According to Pfizer, approximately 9.5% of U.S. adults aged 18 to 49 have underlying chronic conditions that increase their risk of severe disease, a figure that rises to 24% among adults aged 50 to 64.
Market performance and future outlook
In 2022, Abrysvo generated sales of US $890 million, while GSK’s Arexvy reached 1.2 billion pounds sterling (approximately US $1.5 billion).
Following the CDC’s revised recommendations, GSK has adjusted its 2024 sales projections downward. Despite this, the recent approval for Abrysvo allows Pfizer to compete vigorously in the market.
Aamir Malik emphasized, “With this approval…Abrysvo is now the only RSV vaccine indicated for adults aged 18 to 49 at increased risk for the disease, expanding on its existing indications for older adults and pregnant women.”
