Public Health

New FDA-approved RSV shot for babies and CDC's ACIP meeting recap with Sandra Fryhofer, MD


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The CDC’s Advisory Committee on Immunization Practices (ACIP) recommended a new monoclonal antibody shot that can protect babies from RSV. The AMA’s ACIP liaison, Sandra Fryhofer, MD, joins to discuss the recommendation and details of the shot, including who should get it, how often and what the side effects are. AMA Chief Experience Officer Todd Unger hosts.

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  • Sandra Fryhofer, MD, immediate past chair, AMA Board of Trustees; AMA’s ACIP liaison

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Unger: Hello and welcome to the AMA Update video and podcast. Today, we're talking about a new shot that can protect babies from RSV, or Respiratory Syncytial Virus, recommended just last week by ACIP, the CDC's Advisory Committee on Immunization Practices. And here with us today is the AMA's in-house immunization expert, our AMA ACIP liaison and the AMA's immediate past board chair, Dr. Sandra Fryhofer. I'm Todd Unger, AMA's chief experience officer in Chicago. Dr. Fryhofer, thanks for joining us today.

Dr. Fryhofer: Well, thanks for having me.

Unger: Well, I'm eager to hear more about this new shot that can be life saving for babies.

Dr. Fryhofer: Well, it's called nirsevimab, and it's a type of immunization that can protect babies from getting RSV. But it's not a vaccine. It's a longacting monoclonal antibody. Nirsevimab was licensed by FDA on July 17 under an accelerated approval pathway because it was considered a breakthrough therapy and it is. This product was developed jointly by pharmaceutical companies Sanofi and AstraZeneca and will be sold under the brand name Beyfortus.

Unger: Well, let's talk a little bit about how serious RSV is for children and which babies are at the highest risk for severe complications.

Dr. Fryhofer: Well, RSV is the most common cause of hospitalization in infants in the United States. For some, it just causes a nasty cold. But for others, particularly the very young and the very old, it can lead to pneumonia, bronchiolitis and can be life threatening. RSV kills between 100 to 300 children under the age of five in the U.S. each year. Most infants, 68%, are infected in their very first year of life. And 79% of children less than two years old who get RSV have no underlying medical conditions.

This means all young infants are at risk of RSV. In fact, most of the hospitalizations for RSV are in healthy, full term infants. RSV hits babies hardest in the first months of life and that's when we see the highest hospitalization rates. And as children get older, the risk of hospitalization decreases. Babies that are premature and also those with chronic lung disease or prematurity and those with congenital heart disease are at highest risk of severe RSV disease.

Unger: So Dr. Fryhofer, who can get the shot? And how often is it recommended?

Dr. Fryhofer: It's a single shot and it's long lasting. And it can be given with other age-appropriate childhood vaccines. Studies have shown protection last for 150 days. That's about five months. And the RSV season usually lasts around four to five months. RSV infections, just like flu, are usually seasonal, starting in the fall, peaking in the winter. However, the RSV season in Alaska is less predictable and often lasts longer than the national average.

FDA has licensed this monoclonal antibody for babies entering their first RSV season. It's also FDA approved for little ones up to 24 months old in their second RSV season if they remain vulnerable to severe RSV. And as you said, ACIP, CDC's Advisory Committee on Immunization Practices, met last week and they voted on August 3 and recommends a dose of nirsevimab for babies under eight months old entering their first RSV season. ACIP also recommends a protective dose in their second RSV season for older babies, those 8 to 19 months old, who remain at risk of severe RSV infection.

Unger: Well, let's talk about that a little bit more because there is that first season and second season. Which babies should receive it during their second RSV season? And what are the kind of conditions that predispose babies and young children to increased vulnerability to RSV?

Dr. Fryhofer: Well, a protective dose during the second season was recommended for children aged 8 to 19 months old with chronic lung disease or prematurity. And this would include babies who required medical support with chronic steroid therapy, diuretics or supplemental oxygen at any time in the six months before their second RSV season. It's also recommended for children with cystic fibrosis with severe lung disease.

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And this would include children previously hospitalized for lung issues, as well as those that have abnormalities on chest imaging. A dose is also recommended for children with immunocompromising conditions, and also for American Indian and Alaska Native children aged 8 to 19 months old entering their second RSV season. The RSV hospitalization rate for American Indian and Alaska Native children is 4 to 10 times that of the general population.

Unger: Wow. That is really a surprising statistic. It's so important, then, about this new shot. Dr. Fryhofer, what do we know about how well it works?

Dr. Fryhofer: Well, FDA approval was based on three clinical trials. Two of them looked at incidents of medically attended RSV lower respiratory tract infections for 150 days. That's about five months after administration. And one study looked at preterm infants. Another study looked at term and late-preterm infants. The third study supported its use in children up to 24 months old who remained vulnerable to severe RSV.

ACIP also reviewed all the data, and its efficacy is pretty amazing. For infants born during or entering their very first RSV season, nirsevimab was 79% effective against RSV medically attended lower respiratory tract illness and 80% effective at preventing hospitalization. And no specific safety concerns were identified.

Unger: That's good news. Dr. Fryhofer, what should physicians be communicating to patients about potential side effects and safety?

Dr. Fryhofer: Well, side effects include rash and injection site reactions. And just like other monoclonal antibody preparations, they've included warnings about possible serious hypersensitivity reactions, including anaphylaxis. However, ACIP review did not detect any concerning safety signals.

And since this is a monoclonal antibody, reporting of any adverse events is a little bit different. If there's an adverse reaction when nirsevimab is co-administered with a vaccine, you should contact VAERS, which is CDC's Vaccine Adverse Event Reporting System. However, if there's an adverse reaction following administration without co-administration of another vaccine, you should submit a report to FDA's MedWatch.

Unger: And what about the cost of the treatment?

Dr. Fryhofer: It's expensive. And at the ACIP meeting, Sanofi representatives quoted a probable price point of $495 a dose for private sector patients and $395 a dose for public programs, like VFC, the Vaccines For Children program. The product comes in a single, prefilled syringe. It has to be kept refrigerated, but it can be left at room temperature for up to eight hours.

The shot is given IM and comes in both a 50 milligram and 100 milligram prefilled syringe. For the first-season dose, the size of the dose depends on the weight of the child. And the bigger the baby, the higher the dose needed. Sanofi did clarify that the 50 milligram dose and the 100 milligram single-dose syringes will be the same price. The dose for older children, those entering their second RSV season, is 200 milligrams. So the cost of that second season dose is double, so nearly $1,000 for that second-season protective dose.

Unger: All right. Dr. Fryhofer, you talked about at the beginning of our conversation that this is not a vaccine. And I think for a lot of people that term monoclonal antibodies is probably just familiar from our COVID era. But I think what you're saying is this is still considered immunization. And I'm curious if you could talk a little bit about the difference.

Dr. Fryhofer: Well, it's sort of a subtle nuance. And this came up at the AICP meeting. If you think about it, immunity means protection against disease. If you are immune, it means you can be exposed to a disease and not get it. Immunization is a process by which a person becomes protected against the disease.

So with a vaccine, you administer a preparation to stimulate the body's own immune response to protect against a specific disease. That is vaccination-induced immunity. These monoclonal antibodies provide passive immunity. They're laboratory-made proteins that mimic the immune system's ability to fight infection. Both vaccines and monoclonal antibodies are considered to be immunizations.

Unger: All right. Well, we've covered a lot for the younger end of patients. But of course, RSV is also a major threat to older patients. And RSV vaccines were recently recommended for older adults. Dr. Fryhofer, can you just review the recommendations there?

Dr. Fryhofer: Well, RSV is to blame for as many as 60,000 to 120,000 hospitalizations and 6,000 to 10,000 deaths among adults 65 and older each year. And the first-ever vaccines for RSV were FDA approved in May 2023 for adults 60 and older. Both have now been recommended by ACIP for those 60 and older under shared clinical decision, making meaning you and your patient have to decide. Risk of severe RSV disease is increased in older adults with chronic lung diseases, such as COPD and asthma, those with heart problems like congestive heart failure and coronary artery disease, and also in those with kidney problems, liver disorders, blood disorders, neurological disorders and other endocrine problems, including diabetes.

Unger: Now, what about an RSV vaccine during pregnancy? Where does that stand? And what other kinds of protective treatments might be available for babies?

Dr. Fryhofer: Well, an RSV vaccine to be administered during pregnancy is still under review by FDA. And the thought is by giving the vaccine late in pregnancy, mom's antibodies could be passed on to the baby, protecting baby during those first few months of life. A different monoclonal antibody, palivizumab, brand name Synagis, is already available. But it's shorter acting, and protection only lasts about a month. And it's only been licensed for high-risk infants.

And it's extremely expensive. A single dose can cost thousands of dollars. And monthly administration can cost between $5,000 to $10,000 a year.

Unger: All right. Thanks so much for all this perspective. Why don't we summarize. Any final thoughts?

Dr. Fryhofer: Well, nirsevimab is the first-ever immunization against RSV that's available to all infants. It's new. It's expensive. And the final price point is in the hands of the pharmaceutical companies. And price could be a barrier to this lifesaving protection.

Getting insurance companies to pay for it may be challenging. Under ACA, the Affordable Care Act, government officials confirmed it will be covered like other ACIP-recommended immunizations with no copay. However, even under ACA, there is a time lag between ACIP recommendations and when insurance coverage kicks in.

CDC determined that nirsevimab was eligible for inclusion in the VFC, the Vaccines For Children program, and for coverage in the childhood immunization schedules if recommended by ACIP. And just last week, it was. VFC coverage means greater equity and makes this protection available to uninsured and underinsured children. Studies show nirsevimab is highly effective at preventing RSV lower respiratory tract infections and hospitalization. Widespread use of it could prevent many RSV hospitalizations and save lives, but only if these little babies have access to it and then can receive it.

Unger: Well, Dr. Fryhofer, that's really good news, given the seriousness of the condition and the number of folks that are affected by this. Thank you so much for bringing us the news. That wraps up today's episode. We'll be back with another episode soon. And you can find all our videos and podcasts at Thanks for joining us again today. Please take care.

Disclaimer: The viewpoints expressed in this video are those of the participants and/or do not necessarily reflect the views and policies of the AMA.