Pfizer says maternal RSV vaccine prevents infection in infants

Pfizer reported topline data from a phase 3 trial of its respiratory syncytial virus vaccine for pregnant women, which showed high vaccine efficacy in newborns.

The company previously published results from the phase 2b portion of the study — called the Maternal Immunization Study for Safety and Efficacy (MATISSE) — in April, which found that infants born to mothers who were vaccinated with the RSVpreF vaccine received antibodies through the placenta.

According to data reported Tuesday by the company, the vaccine’s efficacy against severe medically attended lower respiratory tract illness (MA-LRTI) was 81.8% (CI: 40.6%-96.3%) through newborns’ first 90 days of life and 69.4% (CI: 44.3%-84.1%) over a 6-month follow-up period.

The trial also found a clinically meaningful efficacy of 57.1% (CI, 14.7%-79.8%) for nonsevere MA-LRTI among infants from birth through the first 90 days of life, which declined to 51.3% (CI, 29.4%-66.8%) over the 6-month follow up period.

Annaliesa Anderson, PhD, senior vice president and chief scientific officer for vaccine research and development at Pfizer, said the company was “thrilled” by the data.

“This is the first-ever investigational vaccine shown to help protect newborns against severe RSV-related respiratory illness immediately at birth,” Anderson said in a press release. “We look forward to working with the FDA and other regulatory agencies to bring this vaccine candidate to expectant mothers to help protect their infants against severe RSV during their most vulnerable first 6 months of life, which has the highest burden of RSV illness in infants.”

Eric A.F. Simões, MD, clinical professor of pediatric infectious diseases at the University of Colorado School of Medicine and Children’s Hospital Colorado, Aurora, said in the release that the vaccine could have a “significant impact” on the disease throughout the world.

“Every year we see high levels of RSV cases among babies in the U.S., with some regions reporting hospital admission rates higher than normal this year,” Simões said. “A maternal vaccine with high efficacy that can help protect infants from birth could substantially reduce the burden of severe RSV among newborns through 6 months of age, and if approved by regulatory authorities, will likely have a significant impact on disease in the U.S. and globally.”

Pfizer said it plans to submit a biologics license application to the FDA by the end of this year for the vaccine candidate.

The report came less than 2 weeks after the company announced that the vaccine was effective in adults.