FDA Panel Unanimously Endorses New RSV Antibody Drug for Infants

A colorized scanning electron micrograph shows human respiratory syncytial virus (RSV) virions shedding from human lung epithelial cells. (NIAID via The Epoch Times)

A panel of outside advisers to the U.S. Food and Drug Administration (FDA) voted in favor of approving a preventative antibody treatment for respiratory syncytial virus (RSV) in newborns and infants.

The unanimous vote by 21 members of the FDA’s Antimicrobial Drugs Advisory Committee (AMDAC) on Thursday brings the monoclonal antibody, nirsevimab, closer to final approval by the FDA.

All on the advisory panel agreed that benefits of the drug, nirsevimab, outweigh the risks in preventing RSV infections for newborns and infants in their first RSV season.

In a separate 19-2 vote, the panel backed the therapy's use in children aged up to two years who are vulnerable to severe illness through their second RSV season.

The FDA does not have to follow the panel's recommendations but generally does.

Nirsevimab, sold under the brand name Beyfortus, is made by AstraZeneca, and would be marketed by Sanofi. It's already approved for use in Canada, the United Kingdom, and the rest of Europe.

First Treatment For All Newborns, Infants

Currently, the only approved preventative treatment in the United States against RSV for infants is palivizumab—sold under the brand name Synagis. However, it's targeted toward pre-term infants or high-risk infants and children. The drug provides short-term protection and is given as monthly injections.

In contrast, nirsevimab is a long-acting treatment, expected to be given once every season to prevent infection.

If approved, nirsevimab would be the first preventative treatment designed to protect all newborns and infants in their first RSV season.

Because it is a monocloncal antibody, nirsevimab is not referred to as a vaccine.

An AMDAC panel member, Nimish Patel, said nirsevimab "is probably the closest thing to an RSV vaccine that we have and it really moves the field forward." 

Patel, a professor of clinical pharmacy at the University of California, San Diego, also said that the once-seasonal dosing schedule is a "huge advance."

Individual FDA reviewers said in a briefing document (pdf) that three late-stage clinical trials spanning over 3,600 participants showed that a single dose of nirsevimab was safe, and was consistently effective against RSV through the entire RSV season.

A small group of healthy and pre-term infants developed a rash as a side effect. Another small group at risk of severe RSV developed a fever. The overall rates of adverse events were comparable between nirsevimab and placebo.

RSV

RSV is a common respiratory virus that usually causes mild, cold-like symptoms, from which most people recover in a week or two, according to the Centers for Disease Control and Prevention (CDC).

But the disease can be serious for some, including infants and older adults. The virus is the most common cause of bronchiolitis and pneumonia in children younger than 1 year old in the United States. It's also the leading cause of hospitalization in the same age group in the country.

“Nirsevimab builds on AstraZeneca’s strong science, leadership in RSV and commitment to addressing the needs of the most vulnerable,” Iskra Reic, AztraZeneca’s executive vice president for vaccines and immune therapies, said in a statement.

A rise in the number of children suffering from RSV in the United States was recorded in late 2022, leaving some hospitals across the country overwhelmed as the COVID-19 pandemic subsided.

The FDA advisory panel's latest endorsement for nirsevimab for infants comes several weeks after a separate group of advisers to the FDA supported Pfizer’s maternal RSV vaccine, intended to protect their newborns, despite concerns the shot could result in premature births.

It is not known how the treatment works in infants whose mothers have received experimental RSV shots.

"I think there will need to be studies that are done to figure out when one is more useful than the other," advisory panel member Karen Kotloff said.

Reuters contributed to this report.