Medication to Prevent RSV
Nirsevimab is an injectable medicine to help prevent respiratory syncytial virus (RSV) infections in babies. Just one or two shots can boost your baby’s immunity. This will keep your baby safe throughout the RSV October to March season.
"Nirsevimab protects babies from RSV in the first 8 months of life. Some babies and toddlers may qualify or need additional doses to help keep them safe and healthy. Here at Cook Children's, we gave many babies medicine in the 2024-2025 RSV season. These babies were 72% less likely to need to stay in the hospital. They were also 62% less likely to get sick with RSV." – Alice Phillips, M.D., a pediatrician at Cook Children's
What is RSV?
Respiratory syncytial virus is a very common illness that spreads very easily. 7 out of 10 babies will get RSV before the age of 1. Like the flu and other respiratory viruses, it spreads easily through the air when a sick person coughs or sneezes. A sick person may leave behind germs on things they touch. Others can get these germs on their hands if they touch doorknobs, faucets or toys after a sick person does.
You can get RSV at any age. You can also get it many times throughout your life. For most people, the symptoms are just like having a bad cold. RSV can be serious for very young babies, for young children with underlying medical conditions or diagnoses, or very old people. Sometimes it will even require a hospital stay and help with extra oxygen or a ventilator (a machine that forces air into and out of a person's lungs. Each year, about 1 in 50 babies with RSV end up in the hospital. This can happen even to healthy, full-term babies. When older kids and adults get RSV, it mainly affects their ears, nose, and throat - like a head cold. When babies get RSV, it also affects the tiny airways in their lungs. Those smaller airways (bronchioles) can swell and make extra mucus. This makes it very hard for a baby to breathe and breastfeed or use a bottle.
RSV care and education Información sobre el RSV
RSV prevention
The FDA approved nirsevimab (Beyfortus™) in 2023. Researchers tested nirsevimab in three separate clinical trials. In all three, they found it was safe and worked well. It lowered the risk of a hospital stay by up to 75 percent for full-term babies. It is similar to another medicine that we have given premature infants for many years. We know it is safe. That drug, palivizumab, also helped prevent RSV. However, we have to give it in several monthly shots. We can give nirsevimab one time.
"With this medicine, we'll be able to keep most babies out of the doctor's office and out of the hospital," – Alice Phillips, M.D., a pediatrician at Cook Children's
Nirsevimab and monoclonal antibodies
When a healthy adult or older child gets a virus the body recognizes the virus as an invader. The immune system then makes a special protein that will learn and attack this virus. We call this protein an antibody. Nirsevimab (Beyfortus™) is a medicine made of monoclonal antibodies. Monoclonal just means they are man-made. They work just like the ones the body makes on its own.
Every day, people touch or breathe in many different types of infections. The immune system is always busy making new antibodies to fight off these infections. Newborns do not have a good supply of antibodies yet. They may not have the ones they need to fight off RSV. Nirsevimab gives a baby the antibodies they need to fight off RSV for up to five months. This medicine is not a vaccine – it is different. A baby cannot "catch" or get sick with RSV from it.
Who should get Nirsevimab?
We suggest a single shot of nirsevimab for:
- All babies younger than 8 months born during or entering their first RSV season (usually October to March).
- High risk babies and young children ages 8 to 19 months who are entering their second RSV season.
High risk babies and children are those who:
- Were born early at less than 32 weeks
- Were born with severe heart disease
- Have nerve or muscle disease that increase risk of RSV
- Have Down syndrome or other genetic conditions that increase risk of RSV
- Do not have a strong immune system
- Have severe, ongoing lung disease
- Have cystic fibrosis
- Are American Indian or Alaskan Native
Common questions
There are currently two RSV vaccines — Arexvy™ and Abrysvo™. The FDA approved these for adults over 60 years old. We also recommend Abrysvo for women who are 32 to 36 weeks pregnant. These are traditional vaccines that stimulate the immune system to recognize the RSV virus. The vaccine helps prevent infection and keep symptoms mild if someone does get sick.
The monoclonal antibody shot for babies works differently. It gives ready antibodies to protect your baby. After their first RSV season, your baby's immune system should be stronger. Your baby will be able to make their own antibodies.
"All medicines come with some risk of side effects, and nirsevimab is no different," says Dr. Phillips. "But overall, babies handle this medicine very well." In the clinical trials, only 1 percent of babies had any side effects. Any side effects were mild. Most common was a slight rash or pain at the injection site.
If you're concerned about side effects, talk to your pediatrician about the pros and cons of this medicine for your baby.
Nirsevimab is very similar to an older medicine that we have used for years. Both are shots of pre-made antibodies to protect babies and children who can't yet make their own. Nirsevimab is an improved version of the original medicine.
"We've been using palivizumab safely for over 20 years to help prevent RSV in babies born early and other at-risk infants. Parents can have confidence in that history." – Alice Phillips, M.D., a pediatrician at Cook Children's
The main difference is how long they protect against RSV. Palivizumab's protection only lasts a month. Babies need monthly shots of palivizumab all winter. Nirsevimab is a single shot at the start of RSV season.
We still use palivizumab for children that are at risk for getting very sick with RSV. Our pediatricians can help you decide which medicine is right for your baby.
The FDA approved nirsevimab for babies 8 months and younger. Most children can build up their own antibodies to protect them from RSV after an RSV season. They no longer need the monoclonal antibodies they'd get from the shot. Some older children with severe chronic illness may be able to get it.
If your baby is born right before or during the RSV season, they should get the medicine this year. We only suggest a second shot next RSV season for children who may get very sick from RSV. This group includes children with a weak immune system or serious lung disease or cystic fibrosis.
Nirsevimab is a monoclonal (man-made) antibody. It offers passive immune support to protect from illness. It is not the same as a "vaccine". Vaccines cause an active immune response in the body. But, we use this medicine to prevent illness. This is the same reason we use vaccines. Some groups may call nirsevimab a vaccine. The medicine offers long-lasting protection from RSV. It can protect for at least 5 months. This is about how long a typical RSV season lasts. Nirsevimab is part of our Vaccines for Children program.
Yes. We do not expect Nirsevimab to affect the immune response to other vaccines. Vaccine side effects were the same with or without nirsevimab.
We expect protection for at least 5 months. This is about the length of an RSV season.
We recommend Nirsevimab even if your child has been sick with RSV. Ask your child's doctor if you have any questions or concerns.