Pfizer has received the US Food and Drug Administration (FDA) approval for its Respiratory Syncytial Virus (RSV) vaccine candidate, Abrysvo, to prevent lower respiratory tract disease LRTD and severe LRTD caused by RSV in infants.

Abrysvo is an unadjuvanted, bivalent RSV prefusion F (RSVpreF) vaccine that contains two preF proteins to optimise the protection against RSV A and B strains.

In May this year, the vaccine was already approved in the US for the prevention of LRTD caused by RSV in individuals aged 60 years or above.

The current FDA approval expands its indication to include infants from birth up to six months of age, through active immunisation of pregnant women at 32 through 36 weeks gestational age.

The expanded approval follows the CDC Advisory Committee on Immunization Practices (ACIP) recommendation for Abrysvo in adults 60 years of age and older, in June 2023.

Abrysvo has received the FDA Breakthrough Therapy Designation and EMA’s CHMP recommendation and is under review by regulatory authorities in Japan and Canada, said Pfizer.

Pfizer vaccine research and development senior vice president and chief scientific officer Annaliesa Anderson said: “Abrysvo’s approval as the first and only maternal immunization to help protect newborns immediately at birth through six months from RSV marks a significant milestone for the scientific community and for public health.

“We are incredibly grateful to the clinical trial participants and study investigator teams around the world, as well as our Pfizer colleagues, for their commitment to making this vaccine available.

“Today, a long-sought-after goal to deliver a maternal vaccine that will help protect infants six months of age or younger – when they are at greatest risk of possible serious consequences from RSV – has been achieved.”

The FDA expanded approval is supported by data from the Phase 3 MATISSE clinical trial, a randomised, double-blinded, placebo-controlled study of Abrysvo.

The Phase 3 study evaluated the efficacy, safety, and immunogenicity of the vaccine against LRTD and severe LRTD due to RSV in infants and healthy people vaccinated during pregnancy.

In addition, Pfizer has launched two additional clinical trials of Abrysvo, one in children at higher risk for RSV disease, aged two years to 18 years.

The second clinical trial is evaluating adults, aged 18 to 60 years, who are at elevated risk for RSV due to inherent medical conditions, and who are immunocompromised.

The US FDA requires the company to conduct post-marketing studies to evaluate the serious risk of preterm birth and hypertensive disorders of pregnancy, including pre-eclampsia.

FDA Centre for Biologics Evaluation and Research director Peter Marks said: “RSV is a common cause of illness in children, and infants are among those at highest risk for severe disease, which can lead to hospitalisation.

“This approval provides an option for healthcare providers and pregnant individuals to protect infants from this potentially life-threatening disease.”