Last year, RSV sent thousands of babies to the hospital—but this year was supposed to be different. The U.S. Food and Drug Administration (FDA) approved a new antibody drug, nirsevimab (sold under the brand name Beyfortus), which babies would get to protect them from infection. But in late October, just as the RSV season was getting started, the U.S. Centers for Disease Control and Prevention (CDC) alerted doctors that the drug was in short supply.

I called a bunch of pediatricians around the country, who said that most babies are not at high risk of developing complications because of RSV. That means parents can protect them by keeping them away from sick people and crowded situations, and by washing their hands often. But having the drug could reduce infections and complications from the disease. Here’s what the doctors shared about why doses are so hard to get, and what options they're offering worried parents:

• Because nirsevimab is recommended for any baby up to eight months old by the time they hit their first RSV season, which runs from November to March, there is a backlog of babies, born as far back as March, who are eligible to get the shot. Their parents are showing up all at once for their dose, which is stretching supply.
• The CDC is recommending that scarce doses are used for the highest risk babies, which includes preemies, those under six months old, and those with heart or lung conditions.
• This year, the FDA approved a vaccine for pregnant women that protects newborns from the day they're born. Doctors recommend anyone giving birth in the coming months get vaccinated between the 32nd and 36th weeks of pregnancy; that way, their babies won’t need to get nirsevimab.