Breaking News – because of limited supplies of Beyfortus, the CDC has proposed interim recommendations to prioritize 100mg doses to infants under 6 months of age and those with high risk conditions. (see below)
Parents have a lot of things to be concerned about when they have a new baby…
Soon though, they hopefully won’t have to worry about their baby getting sick with RSV or Respiratory Syncytial Virus, as we have new tools for preventing RSV in babies and toddlers.
RSV in Babies and Toddlers
Before we talk about these new tools for preventing RSV, a little reminder about why RSV is such a concern for many parents and their pediatricians.

RSV is a life-threatening respiratory infection!
It typically begins to spread in September or October, with cases peaking in December to mid-February, and finally stopping by April to mid-May.
“In the most severe cases, a person may require additional oxygen, or IV fluids (if they can’t eat or drink enough), or intubation (have a breathing tube inserted through the mouth and down to the airway) with mechanical ventilation (a machine to help a person breathe).”
RSV Symptoms and Care
And while it may just cause a minor cold in some people, in others it can lead to a visit to the ER, a stay in ICU, or worse. And even when RSV doesn’t lead to a visit to the hospital, when it causes inflammation of the lungs (bronchiolitis), which is most common in children younger than 12 months, these children can have severe coughing, trouble breathing, and wheezing that lasts for weeks.
Preventing RSV in Babies and Toddlers
So how do you prevent your baby from getting RSV?
As with other respiratory infections, one way would be to simply keep away from anyone who might be sick with RSV symptoms. Of course, this isn’t practical, as with many other viral infections, people infected with RSV are contagious a few days before they have any symptoms and they continue to be contagious for up to 8 days (and sometimes much longer and even after their symptoms have gone away).
“RSV can survive for many hours on hard surfaces such as tables and crib rails. It typically lives on soft surfaces such as tissues and hands for shorter amounts of time.”
RSV Transmission
But can’t we already prevent RSV with Synagis? Yes! Synagis, an RSV monoclonal antibody has been available since 1998, but it requires a monthly injection, is only approved for very high risk infants, including pre-term infants born before 29 weeks and preterm infants with CLD of prematurity, etc., and costs nearly $6,000 per season!
We now have better options, including:
- Beyfortus (nirsevimab) – an RSV monoclonal antibody injection that can be given as a one time dose to all infants who are younger than 8 months and born during, or entering, their first RSV season and high risk children between the ages of 8 and 19 months entering their second RSV season
- Abrysvo – an RSV vaccine approved for seasonal use (September to January) at 32 through 36 weeks gestational age of pregnancy
We also have a problem…
Since both Beyfortus and Abrysvo were only just recently approved, they might not be widely available and we may be facing another RSV season this year. Even more of a problem, since they are new, even if you can find a dose, you may have a hard time getting your insurance company to pay for it!
Neither is cheap either – Beyfortus costs about $495 a dose and Abrysvo costs about $295 a dose.
Questions about Abrysvo and Beyfortus
If you have questions about Beyfortus and Abrysvo, you aren’t alone…
We hopefully have some answers for the most common questions though.
Why are Beyfortus and Abrysvo only given seasonally?
Both products provide antibodies to children and these antibodies only last about six months. Since RSV is seasonal, it is important to time when you give Beyfortus and Abrysvo to maximize when your child will be protected.
If I received Abrysvo when I was pregnant, can my baby get a Beyfortus shot?
In general, only one of these would be used, with a few exceptions. If a mother received her dose of Abrysvo and delivered within 2 weeks, before the dose became effective, then her baby should probably receive Beyfortus. And a high risk infant should likely receive Beyfortus during their second RSV season, even if their mother received Abrysvo.
When are Abrysvo and Beyfortus given?
Abrysvo is seasonally given at 32 through 36 weeks gestational age of pregnancy to protect babies after they are born.
Because it is also given seasonally, Beyfortus can be given:
- to all newborns in their first week of life (can even be given during before discharge from hospital when born) just before and during RSV season (October to March)
- to all newborns and infants less than 8 months of age just before and during RSV season, however, because of limited supplies, infants under 6 months and those who are high risk are now getting priority
- to high risk infants and toddlers aged 8 to 19 months just before and during RSV season
And since the highest RSV hospitalization rates are in first months of an infant’s life, it is best to get your baby their dose as early as possible.
Can Abrysvo and Beyfortus be given with other vaccines?
Yes. Coadministration is safe and doesn’t interfere with other vaccines.
Can infants get both Synagis and Beyfortus?
Since the protection from Synagis only lasts for 4 weeks, your child can get a dose of Beyfortus (at least 4 weeks after their last dose of Synagis). This will protect them for the rest of RSV season.
Can children get Beyfortus if they have already had RSV?
Unfortunately, a natural infection with RSV does not provide long lasting protection. In fact, your child may get RSV again, within 2 months of already having had RSV. So yes, an infant could get Beyfortus even if they have already had RSV this season.
“Severe disease is evident in children undergoing a secondary RSV infection at a young age suggesting that immunity generated after natural infection does not confer protection against severe disease and that age, rather than experience of infection, is the most important factor in disease severity.”
Immunity to RSV in Early-Life
And of course, an older, high risk child should get Beyfortus even if they had RSV last season.
Which older children are considered high risk and need Beyfortus?
Children can also get Beyfortus if they are between the ages of 8 to 19 months and:
- who have chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the RSV season
- are severely immunocompromised
- have cystic fibrosis with either 1) manifestations of severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable) or 2) weight-for-length <10th percentile
- are American Indian or Alaska Native
If getting a second dose, it should be at least 5 months after their first dose, which shouldn’t be an issue since Beyfortus is only given once per season.
Is Beyfortus a vaccine?
Beyfortus is a monoclonal antibody shot.
“CDC has determined that nirsevimab is eligible for inclusion in the childhood immunization schedule and Vaccines for Children program.”
Nirsevimab: Implementation Considerations
Unlike traditional vaccines which stimulate the production of antibodies in our bodies (active immunity), Beyfortus simply provides passive immunity. The antibodies are in the shot!
Unfortunately, the protection from antibody shots wears off once the antibodies leave your body, as you don’t make any new ones.
Who shouldn’t get Abrysvo and Beyfortus?
Abrysvo and Beyfortus are contraindicated in those with a history of severe allergic reaction (e.g., anaphylaxis) after a previous dose or to a product component.
Who else can get an RSV vaccine?
Two Respiratory Syncytial Virus (RSV) vaccines, Arexvy and Abrysovo, are approved for people ages 60 years and older.
Where can I report side effects after giving or getting Arysovo or Beyfortus?
You can report side effects:
- after administration of Beyfortus alone to MedWatch
- after the coadministration of Beyfortus with a vaccine(s) to the Vaccine Adverse Event Reporting System (VAERS)
- after administration of Abrysvo to the Vaccine Adverse Event Reporting System (VAERS)
The most commonly reported side effects from Beyfortus have been described as minimal to small and include injection site reactions (0.3%) and rash (0.9%).
The most commonly reported side effects from Abrysvo are pain at the injection site, headache, muscle pain, and nausea.
Also, to address a numerical imbalance in preterm births in Abrysvo recipients that was observed compared to placebo recipients in two clinical studies, FDA has required the manufacturer to conduct post-marketing studies to assess preterm birth and hypertensive disorders of pregnancy, including pre-eclampsia. Note that since Abrysvo isn’t given before 32 weeks, any potential risk with extreme preterm births is avoided as this study is done.
Can I give an older infant two 50mg doses?
No. This would take away doses from two younger infants!
Will this be our last big RSV season?
We can hope!
RSV isn’t going away though, as it will still cause colds in older children and adults who aren’t vaccinated and protected. And most of the world doesn’t have access to Abrysvo and Beyfortus…
What to Know About Abrysvo and Beyfortus
Having Abrysvo and Beyfortus this RSV season is exciting news!
Since they are so new, expect some challenges finding a dose though. If you are interested in either, call your insurance company and ask about coverage – telling them you want and expect them to be covered, and then call your provider to see when they will have them available.
What if you don’t have insurance? You can still get Beyfortus through the Vaccines for Children program. Pregnant teens without insurance can also get Abrysvo through VFC.

Are you ready to protect your kids from getting RSV?
More on Preventing RSV in Babies and Toddlers
- CDC – Limited Availability of Nirsevimab in the United States—Interim CDC Recommendations to Protect Infants from Respiratory Syncytial Virus (RSV) during the 2023–2024 Respiratory Virus Season
- Mortality Associated With Influenza and Respiratory Syncytial Virus in the US, 1999-2018
- CDC – RSV Symptoms and Care
- CDC – RSV Transmission
- CDC – Frequently Asked Questions About RSV Immunization for Children 19 Months and Younger
- FDA – FDA Approves First Vaccine for Pregnant Individuals to Prevent RSV in Infants
- Nirsevimab: Implementation Considerations
- FDA – RSV Immunity, Durability, and Reinfection
- Immunity to RSV in Early-Life
- CDC – Respiratory Syncytial Virus (RSV) Preventive Antibody: Immunization Information Statement (IIS)
- Proposed clinical considerations for maternal RSVPreF vaccine and nirsevimab
- Maternal Respiratory Syncytial Virus Vaccination
- The Latest in RSV Protection for Kids: An Antibody Treatment Called Beyfortus
- New RSV Vaccine: How to Protect Your Family Against RSV This Season
- CDC – RSV National Trends