This fall, for the first time, many babies in the U.S. will be eligible to get a shot to fend off RSV, a respiratory virus that can cause serious lung disease in infants and young children.

On Thursday, the Centers for Disease Control and Prevention recommended that all infants under 8 months old receive an injection of nirsevimab, a newly approved monoclonal antibody, as they enter their first RSV season (usually fall through spring). A subset of children up to 19 months at heightened risk of serious RSV disease – including those with chronic lung disease, and American Indian and Alaska Native children – can get a shot in their second RSV season.

"RSV is the leading cause of hospitalizations for infants and older babies at higher risk, and today we have taken an important step to make this life-saving product available," said Dr. Mandy Cohen, director of the CDC, in a statement.

The CDC recommendation follows the FDA approval of nirsevimab last month. A single shot of antibodies was shown in clinical trials to lower the need for medical care from RSV for babies by 70% to 75%. Health officials hope that, with widespread use, the drug can help prevent many of the 58,000 to 80,000 hospitalizations for young children with RSV that occur each year.

Still, there are many hurdles to clear before the drugs show up at hospitals and doctors' offices. "There's a large number of implementation issues that arise with monoclonal antibodies," said the CDC's Dr. Melinda Wharton, at a public meeting of the agency's Advisory Committee for Immunization Practices Thursday. "It's not due to the characteristics of the product itself. It's due to other factors."

High price tag

One issue is the price. The drugmakers AstraZeneca and Sanofi estimate that the shot will cost $495 a dose on the commercial market – which several committee members felt was too high.

"We are extraordinarily disappointed with the price setting of the manufacturer," said Dr. Sarah Long, of the Drexel University College of Medicine.

"We do understand that the companies need to make their profit," said Dr. Katherine Poehling, at Wake Forest School of Medicine, "But I am worried about equity."

Technically, not a vaccine

To make the drug accessible, the CDC is placing nirsevimab in their Vaccines for Children program, which covers the costs for kids who are uninsured. That's a big deal because the drug is technically a therapeutic, not a vaccine.

"This is a new era where we're thinking about prevention more broadly," said Dr. Grace Lee, a professor of pediatrics at Stanford Medicine and chair of the ACIP.

The difference is that while a vaccine trains a person's immune system to make its own antibodies, this shot provides a quick, temporary flood of antibodies directly, which go away after a few months.

Hurdles ahead

Bureaucratically, some states restrict who can give injectable drugs, which means that a health care worker who can give vaccines may not be able to give this shot. There are questions on coding and billing, and how to keep track of these shots so each baby gets one — and only one — dose.

And those that run vaccine programs on state and local levels haven't been looped into the planning, says Claire Hannan, head of the Association of Immunization Managers. "They cannot be expected to deploy critical products, without the information and time needed to execute these programs," says Hannan, who spoke during the meeting's public comment period.

Dr. Marcus Plescia, chief medical officer for the Association of State and Territorial Health Officers, says it may also take awhile for parents to warm up to the new drug. "It's recommended very soon after birth," he says. "A lot of parents are a little bit cautious about wanting to give really young children things. So it may take a little bit of time to really build confidence in the monoclonal antibody."

The drugmakers say nirsevimab – marketed under the trade name Beyfortus – will be launching this fall. But given the hurdles, some doctors are curbing their expectations. "I feel realistically that it will be available. [But] whether it's widely available – I can't speak to that," said Dr. Tochi Iroku-Malize, president of the American Academy of Family Physicians.

CDC officials say these implementation challenges are real but they are surmountable.

Competitors, too

Beyfortus's launch will broaden the protection available for babies. Prior to this approval the only existing preventive drug for RSV was a monoclonal antibody shot called palivizumab, which requires monthly administration and is reserved for babies at high medical risk.

This antibody shot is one of several new drugs and vaccines in development to protect babies and the elderly from RSV. By late August, the FDA is expected to issue a decision on an RSV vaccine to protect newborns that is given to pregnant mothers.