RSV in Babies: Signs, Prevention, and When to Call

RSV in babies usually starts like an ordinary cold, but it can turn into a serious breathing illness within a few days, especially in infants under six months. The good news for the 2026–2027 season is that parents now have two proven ways to protect a newborn: an RSV vaccine during pregnancy or an RSV antibody shot for the baby. Here is what I wish someone had laid out for me, in plain language.

I’m Sk, and my youngest was born in late October, right as RSV season was ramping up. I remember standing in the hospital hallway trying to make sense of “monoclonal antibody” on four hours of sleep. This guide is the calm, organized version of everything I learned from our pediatrician and from the CDC and American Academy of Pediatrics. It is informational only, so please talk with your own pediatrician about your baby.

Key Takeaways

• RSV in babies often begins with a runny nose, a cough and eating less, then can worsen a few days in.
• In very young infants, RSV may show up as fussiness, low energy, poor feeding or pauses in breathing, often without a fever.
• The CDC and AAP advise protecting infants through either a maternal RSV vaccine in pregnancy or an infant RSV antibody. Most babies do not need both.
• Everyday habits such as handwashing, keeping sick visitors away and wiping down surfaces help lower exposure.
• Trouble breathing, not drinking enough, or worsening symptoms mean you should contact your pediatrician or seek care right away.

What Is RSV and Why Does It Hit Babies So Hard?

Respiratory syncytial virus is a common seasonal virus that infects the nose, throat and lungs. For most older kids and adults it feels like a cold. For babies, whose airways are tiny, the swelling and mucus it causes can make breathing hard.

According to the CDC’s page on RSV in infants and young children, an estimated 58,000 to 80,000 children younger than five were hospitalized with RSV each year before infant immunizations became available. The CDC also notes that two to three out of every 100 infants under three months are hospitalized with RSV every year.

The CDC says most children will catch RSV by age two. The younger the baby, the higher the risk of severe illness. Babies born early, and those with chronic lung disease, congenital heart disease, weakened immune systems or certain neuromuscular conditions, face extra risk.

Signs of RSV in Babies to Watch For

This was the part that surprised me most. RSV in babies does not always look dramatic at first. The CDC describes early symptoms as a runny nose, eating or drinking less, and a cough that may progress to wheezing or difficulty breathing.

Symptoms in Babies Under Six Months

In very young infants, the CDC lists irritability, decreased activity, eating or drinking less, and apnea, meaning pauses in breathing longer than 10 seconds. The CDC also points out that many infants will not have a fever with RSV. So a baby without a temperature can still be quite sick.

Breathing Changes That Matter

The Mayo Clinic’s overview of RSV describes short, shallow and rapid breathing, and chest muscles and skin pulling inward with each breath, as signs of more severe infection. Unusual tiredness and irritability matter too.

In our house, I started watching my baby’s belly and ribs with his onesie pulled up. Seeing the skin between the ribs suck in was the moment I knew to call. If you are unsure, a quick call to your pediatrician’s nurse line is always the right move.

When to Seek Care Right Away

The CDC advises seeking medical attention if your child has difficulty breathing, is not drinking enough fluids, or has worsening symptoms. Call emergency services for pauses in breathing, bluish or gray lips or skin, or a baby who is very hard to wake. For babies under two to three months, any fever deserves a same-day call; our guide on when to worry about a baby fever walks through that in more detail.

How RSV Spreads Around the House

The CDC’s explanation of how RSV spreads covers coughs and sneezes, direct contact like kissing a sick child’s face, and touching contaminated surfaces and then your face. RSV can survive for many hours on hard surfaces such as tables and crib rails.

The CDC adds that people with RSV are usually contagious for three to eight days and may be contagious a day or two before symptoms start. Some infants can keep spreading it for four weeks or longer. Older siblings often bring it home from school or childcare, which is exactly how it reached our newborn.

How to Protect Your Baby From RSV This Season

There are two immunization options, and the CDC says most infants will not need both. Your pediatrician and obstetric provider can help you decide which fits your family.

Option One: The Maternal RSV Vaccine During Pregnancy

A pregnant parent can receive a single RSV vaccine (Pfizer’s Abrysvo) late in pregnancy, during weeks 32 through 36, typically in the fall and winter months. The antibodies pass to the baby before birth. According to CDC guidance, a baby born at least 14 days after the vaccine generally does not need the infant antibody too.

Option Two: An Infant RSV Antibody

Nirsevimab (Beyfortus) and clesrovimab (Enflonsia) are long-acting antibodies given as a single shot. They are not vaccines; the antibodies themselves provide protection. The CDC’s infant RSV immunization guidance recommends them for babies under eight months who are born during or entering their first RSV season if the mother was not vaccinated, her status is unknown, or the baby was born within 14 days of the vaccine.

The CDC reports that early real-world data showed nirsevimab was at least 70% effective at keeping babies out of the hospital with RSV. In clinical studies, clesrovimab was 90.9% effective against RSV lower respiratory infection with hospitalization through 150 days. Side effects are usually mild, such as redness or swelling at the injection site.

Timing Matters

In most of the U.S., the CDC says the infant antibody is given October through March. Babies born in that window ideally receive it within their first week, often before leaving the hospital. Babies born April through September are ideally immunized shortly before the season starts, around October or November. It can be given at the same visit as routine vaccines.

What Is New for 2026–2027

In September 2026, the American Academy of Pediatrics released its 2026–2027 RSV recommendations. The AAP continues to recommend immunization for all infants under eight months in their first RSV season unless they are protected through the pregnant parent’s vaccine.

The AAP also expanded which children aged 8 through 19 months qualify for a second-season dose. The new high-risk list includes children born before 32 weeks, children with significant congenital heart disease, certain lung or neuromuscular conditions, and Down syndrome. If your baby was born early or has a chronic condition, ask your pediatrician whether a second-season dose applies.

Everyday Habits That Lower RSV Risk

Immunization is the biggest step, but daily habits still matter. Here is what worked in our home during the first winter:

• Handwashing on arrival. Everyone washes with soap and water before holding the baby. The CDC recommends frequent handwashing and covering coughs and sneezes.
• A kind “not today” rule. Visitors with even a mild cold wait until they feel better. No kisses on the baby’s face.
• Wipe the high-touch spots. Doorknobs, crib rails, changing tables and toys get cleaned often, since RSV lingers on hard surfaces.
• Fresh air. The CDC suggests bringing in outside air or purifying indoor air to reduce respiratory virus spread.
• Siblings’ routine. Big kids wash hands and change clothes after school or childcare before cuddling the baby.
• Childcare questions. If you are touring daycares, ask about illness policies; our guide to choosing childcare for your baby has a checklist.

Caring for a Baby With RSV at Home

There is no specific cure for RSV; care focuses on comfort and keeping your baby hydrated while the virus runs its course. Follow your pediatrician’s instructions, and keep these general points in mind:

• Keep feeds going. Offer breast milk or formula often. Fewer wet diapers is a sign to call your pediatrician.
• Clear the nose gently. Saline drops and a bulb syringe before feeds can help a stuffy baby eat; see our post on relieving baby congestion safely.
• Skip cough and cold medicines. The FDA advises against over-the-counter cough and cold products for children under two. Ask your pediatrician before giving any medicine.
• Keep safe sleep the same. Even when congested, the AAP recommends placing your baby on their back on a firm, flat surface in a bare crib or bassinet. Do not prop the mattress, use inclined sleepers or put pillows in the crib.

The CDC notes that RSV can become more severe a few days into the illness, so keep watching closely even if your baby seemed fine on day one. Trust your instincts; you know your baby best.

Summary

RSV in babies can start as a simple sniffle and become serious within days, particularly for infants under six months, preemies and babies with chronic health conditions. Watch for faster or labored breathing, poor feeding, low energy and pauses in breathing, and remember that fever is often absent in young infants.

This season, both the CDC and AAP support protecting newborns with either a maternal vaccine in pregnancy or an infant antibody shot, with most babies needing only one. Combine that with handwashing, keeping sick visitors away and a steady safe-sleep routine. Most importantly, talk with your pediatrician about which option fits your baby and call them whenever something feels off.

Frequently Asked Questions

How do I know if my baby’s cold is actually RSV?

You often cannot tell from symptoms alone, because RSV starts like a regular cold. What matters most is how your baby is breathing, eating and acting. If breathing looks fast or labored, feeding drops off, or your baby seems unusually sleepy, contact your pediatrician, who can decide whether testing or an exam is needed.

Does my baby need the RSV antibody if I got the RSV vaccine while pregnant?

Usually not. According to CDC guidance, most babies born fourteen or more days after the pregnant parent’s RSV vaccine do not need the infant antibody. There are rare exceptions, such as certain medical conditions, so confirm with your pediatrician.

Can my baby get RSV more than once?

Yes. The CDC notes that repeat infections can happen throughout life. Later infections are typically milder, but babies at higher risk may still need extra protection in their second season, which is why the AAP expanded its second-season recommendations for 2026–2027.

When is RSV season?

In most of the United States, RSV season starts in the fall and peaks in winter, though timing varies by region and year. Warmer places such as southern Florida, Hawaii and Puerto Rico can have different patterns, so check with your pediatrician or local health department.

Is the infant RSV antibody safe to give with other shots?

The CDC says infant RSV antibodies can be given at the same visit as routine childhood vaccines, and side effects are usually mild, like soreness or swelling where the shot was given. Your pediatrician can review your baby’s specific health history with you.

This article is for general information only and is not medical advice. Always consult your pediatrician about your baby’s health, symptoms and immunization choices. If your baby is struggling to breathe, call emergency services right away.