Last night, the US Food and Drug Administration’s (FDA) Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted to support the efficacy and safety of Pfizer’s unadjuvanted bivalent respiratory syncytial virus (RSV) prefusion F vaccine candidate, RSVpreF.

After reviewing all available trial data, VRBPAC voted 14 to 0 in favor of the efficacy of RSVpreF and 10 to 0 in favor of the safety. Through active immunization in pregnant persons, RSVpreF prevents medically attended lower respiratory tract disease (MA-LRTD) and severe MA-LRTD caused by RSV in infants from birth to 6 months of age. 

With this recommendation from VRBPAC, RSVpreF is one step closer to FDA authorization. The vaccine candidate was granted a Prescription Drug User Fee Act (PDUFA) goal date of August 21, 2023, upon which the FDA will likely decide whether to approve Pfizer’s RSVpreF.

Contagion interviewed Iona Munjal, MD, senior director of vaccine research and development at Pfizer. Munjal was on the front lines of the RSVpreF MATISSE (MATernal Immunization Study for Safety and Efficacy) phase 3 clinical trial, and as a pediatrician, she has high hopes for the vaccine’s ability to alleviate the burden of RSV in infants and young children.

“For infants, RSV remains the number 1 cause of inpatient hospitalizations due to respiratory illness,” Munjal explained, “and to this date we have no treatment, so it’s a really frustrating time for parents.”

The world’s first RSV vaccine, GSK’s Abrexvy, recently received FDA approval to prevent RSV-induced lower respiratory tract disease in adults 60 years and older. However, there is still no vaccine for the pediatric population.

Supportive care for RSV, such as breathing and feeding, can be lifesaving. But, Munjal says, “Vaccines, like the Pfizer RSVpreF vaccine, really represent a potential substantial change in the number of infants who would come down with that really scary illness.”

RSV was formally identified in the 1950s, but a failed vaccine in the 1960s seriously stunted further RSV vaccine development. Munjal added, “For years, we hadn’t really understood the protein on the surface of the virus. This F protein that we’re using as the target, we didn’t know its structure. So until we understood it, we couldn’t use it effectively.”

RSVpreF is a maternal vaccine, meaning it is administered to pregnant individuals to ensure babies are protected from birth. “Rather than having babies get the antibody through a shot, you can actual utilize one of the oldest forms of antibody gifting, which is the placenta,” said Munjal.

Munjal noted moms naturally pass antibodies onto their babies when they themselves contract RSV, “But the levels that we cause them to make of antibodies after vaccination are many fold higher than what you’d get from a natural RSV cold.”

“This is a really exciting time for us,” said Munjal, noting that infants, parents, and pediatricians like herself will all benefit if RSVpreF is approved.

This was part 1 of an interview with Dr. Munjal. Come back soon for part 2, in which she discusses why RSV disease is so severe in infants and shares key data from RSVpreF clinical trials.

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