RSV prevention for babies

Why RSV deserves its own plan

By age 2, almost every child has had RSV at least once. For most healthy older kids and adults it is a bad cold. For babies under 6 months, particularly under 3 months, and for preemies of any age, it can move into the small airways of the lungs and cause bronchiolitis, dehydration, and respiratory failure fast enough to need hospital care.

The CDC puts the annual hospitalization number at 58,000 to 80,000 US infants. That is enormous. What changed in 2023 and held through 2026 is that we now have effective tools to cut that number by more than two thirds. Almost no parent uses all of them.

Tool 1: Nirsevimab (the baby antibody shot)

Nirsevimab (brand name Beyfortus) is a long-acting monoclonal antibody given as a single injection. It is not a vaccine. It hands your baby pre-made antibodies that hang around for about 5 months, which conveniently covers the RSV season.

The CDC currently recommends it for every infant under 8 months entering their first RSV season (mostly October through March in the US), and for high-risk infants between 8 and 19 months entering their second season. The clinical-trial efficacy against hospitalization is about 80 percent. Real-world data from the 2023 to 2024 season showed similar performance.

Side effects are mild. Mostly soreness at the injection site and occasional rash. It is funded through the Vaccines for Children program for eligible kids and is covered without copay by most commercial insurance.

Tool 2: The maternal RSV vaccine

Pfizer's Abrysvo is given to pregnant people between 32 and 36 weeks gestation between September and January. Antibodies cross the placenta and protect the newborn through the first 6 months.

You generally pick one path or the other. If you got the maternal vaccine at the right window, your newborn usually does not also get nirsevimab. If you did not, your baby gets nirsevimab after birth. Talk to your OB and pediatrician about timing. Both work. The choice often comes down to scheduling.

Tool 3: Hand hygiene that actually does something

RSV spreads by droplets and by hands that touched a surface with droplets. The virus can survive on hard surfaces for several hours. The fix is unglamorous:

• Wash hands before holding the baby. Every time, with soap, 20 seconds. Hand sanitizer is fine if you are not visibly dirty.
• Anyone with a "just a cold" stays away from a baby under 3 months. Adults often have mild RSV without knowing it.
• Wipe down phones, doorknobs, and the kitchen counter during sick season.
• Older siblings home from daycare go straight to hand washing before approaching the baby.

Tool 4: Smart daycare-season choices

If you have a choice about when your baby enters daycare, fall and early winter are the hardest months. A baby starting daycare at 6 weeks in October will catch nearly every virus in rotation. The same baby starting daycare at 6 months in April will catch fewer, and with more mature lungs.

If you cannot delay, that is fine. Just stack the other tools. Get the antibody shot. Limit non-essential indoor visits. Keep grandparents away if they have any symptoms.

Tool 5: Breastfeeding where it is an option

Breast milk passes maternal antibodies and slightly reduces the severity of respiratory infections in the first year. It is not a force field. Babies who breastfeed still get RSV. But formula-fed babies have a modestly higher rate of severe RSV outcomes in observational studies. If you are mixed feeding or considering, this is one more small reason to keep some breast milk in the picture if it works for your family. If it does not, the other tools still work.

What RSV looks like in a baby

Most babies start with what looks like a regular cold for a day or two: runny nose, cough, mild fever. Around day 3 to 5, RSV can sink into the lower airways. The signs to watch for:

• Fast breathing. Count breaths for a full minute when baby is calm. Over 60 per minute under 2 months, over 50 per minute 2 to 11 months, over 40 per minute over 1 year is fast.
• Working hard to breathe. Belly pulling in under the ribs, nostrils flaring, the skin between the ribs sucking in with each breath (retractions).
• Wheezing. A high whistle on the breath out.
• Color changes. Pale, dusky, or blue around the mouth or nail beds.
• Fewer wet diapers. Under half their usual count over 12 hours is a dehydration flag.
• Pauses in breathing of more than 10 seconds.

When to call

• Any breathing difficulty in a baby under 3 months. Call now.
• Retractions, fast breathing, or color changes at any age. ER.
• Refusing feeds, or has not had a wet diaper in 8 hours.
• Fever in a baby under 12 weeks at any temperature.
• Lethargy, or a baby who is hard to wake.

What does not work

• Cough syrups. The FDA recommends against them in kids under 4. They do not shorten illness and can have side effects.
• Antibiotics. RSV is viral. Antibiotics do nothing unless there is a secondary bacterial infection.
• Vapor rubs on infants. Not safe for babies under 2.
• "Boosting immunity" supplements. There is no supplement that prevents RSV.

The household plan, in one paragraph

Get the maternal vaccine or the baby's antibody shot, whichever the timing supports. Wash hands. Tell sick relatives the visit can wait two weeks. Watch your baby's breathing, not just the thermometer. Call your pediatrician at the first sign of trouble. That is the entire plan.