July 18, 2023: On Monday, the FDA authorized AstraZeneca and Sanofi’s drug that protects newborns and toddlers against the respiratory syncytial virus, leading to the cause of hospitalization among babies in the U.S.

Nirsevimab is the sooner shot approved by the FDA to protect all infants against RSV, yet of whether they are healthy or have a medical condition.

Another dose, named palivizumab, is already on the market. Still, it is given mainly to preterm infants or those with lung and congenital heart conditions that put them at high risk of severe disease. Nirsevimab is also administered as a single injection. This is a significant advantage over palivizumab, administered monthly throughout the RSV season.

Nirsevimab is issued either before or during an infant’s first RSV season. Toddlers up to two years old who remain weak can also receive the shot during their second RSV season.

RSV is a significant public health threat that kills about 100 infants annually, according to a study published in the medical journal JAMA Open Network last year. According to a study published in the Journal of Infectious Diseases, the virus is the leading cause of hospitalization among children less than a year old.

Last fall, a surge in RSV infections overwhelmed children’s hospitals across the U.S. and led to calls for the Biden administration to declare a public health emergency in response.

According to an FDA review, Nirsevimab was increased to 75% effective at preventing lower respiratory tract infections that needed medical attention among babies and 78% effective at stopping hospitalization.

The FDA did not recognize any safety concerns in its review of nirsevimab, though other monoclonal antibodies have been associated with allergic reactions such as skin rashes.

Nirsevimab is a monoclonal antibody that has a similar function to a vaccine. Vaccines stimulate the immune system to produce protective antibodies, while shots like nirsevimab deliver those antibodies directly into the bloodstream.

The fact that nirsevimab is regulated as a drug has created uncertainty about whether the federal Vaccines for Children program will provide the shot for free to families who face financial difficulties. The CDC advisors are expected to examine this issue at their August meeting.

Families might have two choices to protect their infants. Pfizer has developed a vaccine that protects infants by administering the shot to the mother while pregnant. The FDA’s independent advisors suggested Pfizer’s vaccine. The agency is expected to make a final determination on whether to support the shot in August.