FDA advisory panel votes in favor of Pfizer RSV vaccine

The Food and Drug Administration’s (FDA) vaccine advisory panel voted on Thursday in favor of Pfizer’s RSV vaccine on, which would be the first vaccine to protect against the virus in infants if it receives approval.

The 14 voting members on the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) who were present on Thursday voted unanimously in favor of the vaccine.

VRBPAC chair Hana El Sahly said the data presented to the committee was “very convincing” when explaining her “yes” vote.

“If the vaccine actually lives up to the data that we’ve seen today, I can guarantee many infants and their parents will breathe easier in the coming years,” committee member Jay Portnoy said.

This vote comes just weeks after the FDA approved the first-ever RSV vaccine. The shot from GlaxoSmithKline was approved for use in those aged 60 and older.

Pfizer’s version of the RSV vaccine, administered in a single dose, confers protection to infants in an unorthodox manner: The dose is administered to mothers before they give birth so their children can have immunity from the moment they’re born.

In documents submitted to the committee, Pfizer cited five clinical human studies, two of which were conducted with pregnant participants. The company said its vaccines elicited “robust immune responses” in the expecting participants between the ages of 18-49, who were given the immunization in their late second and third trimesters.

The neutralizing antibodies detected in their children were found to be higher in comparison to the placebo group from birth through six months of age — when infants are particularly vulnerable.

All doses and formulations of the vaccine were observed to be “safe and well-tolerated” in a Phase 3 study, according to the company.

While the committee generally spoke favorably of the findings presented by Pfizer, members acknowledged some areas of potential concern.

VRBPAC member David Kim, director of the Department of Health and Human Services’ National Vaccine Program, noted a potential interaction between between Pfizer’s RSV vaccine and the vaccine for whooping cough. Even so, this was found in non-pregnant individuals and the clinical significance of that potential interaction is unclear.

“That will need to be addressed down the line and I’m encouraged by Pfizer and the FDA and their plans to address this concern in the future,” Kim said.

Some adverse side effects that were observed among test participants were “abdominal pain, nausea, and premature delivery” within one month after receiving the vaccine.

Among the test group, 37.1 percent of participants reported adverse side effects, compared to 34.5 percent among the placebo group.

Several committee members expressed a desire for more inquiries into the possible link between the vaccine and preterm births. Pfizer observed the incidence of preterm births in the test group was “numerically” higher but “not statistically meaningful.” 

RSV is an extremely common virus, with the majority of people exposed to it at some point in their early childhood and gaining immunity. In healthy adults, RSV or respiratory syncytial virus normally causes mild cold-like symptoms that go away with self-care and rest.

The U.S. saw an elevated surge of RSV cases among small children and infants last winter.

Many physicians attributied the rise in RSV cases to COVID-19 lockdowns, which kept kids isolated from viral exposure they normally would have encountered.

The rise in hospitalizations and the lack of available vaccines brought attention to the lack of preventive options for parents. Monoclonal antibodies can be administered to infants, but it is usually reserved for extremely high-risk cases.