FDA gives the green light to Merck’s RSV vaccine for infants to compete with Sanofi AstraZeneca.

FDA Approves Merck’s RSV Shot for Infants

On Monday, the Food and Drug Administration (FDA) approved Merck’s new vaccine aimed at protecting infants from respiratory syncytial virus (RSV) during their first season of exposure. This development positions Merck to compete with similar treatments from Sanofi and AstraZeneca.

The FDA’s decision allows Merck to introduce the vaccine, branded as Enflonsia, ahead of the typical RSV season, which generally starts in the fall and continues into spring. The company stated that it expects to begin receiving orders in July, with the aim of ensuring shipments are delivered before the virus spreads significantly.

This approval introduces a new option for physicians to combat RSV, a virus responsible for thousands of deaths among older adults and hundreds among infants annually. Complications from RSV are a major contributor to hospitalizations in newborns.

“We are committed to making [Enflonsia] available in the U.S. before the upcoming RSV season to alleviate the substantial burden this prevalent seasonal virus places on families and health care systems,” said Dr. Dean Li, president of Merck Research Laboratories.

Merck’s vaccine will be in competition with Sanofi and AstraZeneca’s product, Beyfortus, which faced significant shortages during the last RSV season due to high demand.

Both vaccines are monoclonal antibodies designed to deliver protection directly into the bloodstream, although they target different aspects of the virus, making straightforward comparisons challenging.

One notable advantage of Merck’s treatment is that it can be given to infants regardless of their weight, potentially simplifying dosing. In contrast, Beyfortus requires dosage adjustments based on an infant’s weight.

On the same day, Sanofi announced plans to boost the supply of Beyfortus, including shipping earlier in the third quarter. The previous year, Beyfortus generated sales of approximately €1.7 billion ($1.8 billion).

Meanwhile, there are RSV vaccines from other companies, like Pfizer, GSK, and Moderna, but these are intended for adults or pregnant women. The FDA recently halted trials for RSV vaccines in young children while it assesses safety issues.

All manufacturers are now anticipating a meeting of vaccine advisors to the Centers for Disease Control and Prevention (CDC) set for June 25-27. During this meeting, recommendations for RSV vaccines and other immunizations will be discussed.

In clinical trials for Enflonsia, the treatment was shown to lower RSV-related hospitalizations by over 84% and reduce hospitalizations for lower respiratory infections by 90% compared to a placebo in infants up to five months old. It also decreased medically-attended lower respiratory infections by more than 60% during the same period.