Respiratory syncytial virus (RSV) is a common virus that usually causes little more than a cold in older children and adults. In young babies it can reach the tiny airways of the lungs and make breathing and feeding hard work. This guide explains how RSV in babies usually starts, the signs that mean you should see a GP, the signs that need an ambulance, and who can get free RSV protection in Victoria. It draws on advice from The Royal Children’s Hospital Melbourne and the Australian and Victorian health departments.
Key Takeaways
- RSV is the most common cause of bronchiolitis, a chest infection in babies up to 12 months old.
- Most babies are sick for 7 to 10 days and recover at home, although the cough can last up to 4 weeks.
- Any baby under 3 months with a temperature of 38°C or more needs urgent hospital care.
- Call 000 if your baby is struggling to breathe, pauses while breathing, has blue lips or is hard to wake.
- A free maternal RSV vaccine is recommended at 28 to 36 weeks of pregnancy.
How RSV affects babies
RSV is the virus most often behind bronchiolitis. The Royal Children’s Hospital Melbourne describes bronchiolitis as a chest infection in babies up to 12 months old, in which inflammation and mucus build up in the small airways called bronchioles. That makes it harder for a baby to breathe, and harder to feed.
The viruses that cause bronchiolitis spread easily through droplets when someone talks, coughs or sneezes. A baby can catch RSV from an older sibling or adult who has only a runny nose or a mild cough, because the same virus that gives an adult a head cold can cause a chest infection in a baby.
Bronchiolitis can be more serious in babies who were born prematurely, are younger than 10 weeks, are Aboriginal or Torres Strait Islander, or live with chronic lung disease, congenital heart disease, a chronic neurological condition or a weakened immune system.
The first signs to watch for
RSV usually starts like a cold, with a mild cough and a runny or blocked nose. After one or two days the cough tends to get worse and breathing becomes more of an effort. Common bronchiolitis symptoms include:
- fast breathing
- wheezing or noisy breathing
- breathing that looks like hard work: the skin between the ribs or under the neck sucking in, flaring nostrils, or head bobbing in younger babies
- being unsettled and restless
- a temperature of 38°C or more
- trouble feeding because of a blocked nose, mucus or shortness of breath
Symptoms are usually at their worst on the second or third day. Most babies are sick for around 7 to 10 days, and the cough can linger for up to 4 weeks. Our guide to fever in kids covers temperatures in more detail.
Worried about your baby’s breathing or feeding? Our GPs see babies and children seven days a week, and walk-ins are welcome.
When to see a GP about RSV in babies
If you think your baby has bronchiolitis, see a doctor. A GP can usually tell by examining your baby and asking about their symptoms, and tests are not normally needed. The Royal Children’s Hospital advises seeing a doctor if your baby:
- is breathing fast while resting
- is feeding less than half their normal amount
- seems very tired or sleepier than usual
- was born prematurely or is under 10 weeks old
- has a chronic lung, heart or neurological condition or a weakened immune system
- is Aboriginal or Torres Strait Islander
- is still sick after seven days
Harpley Doctors is open Monday to Friday 8 am to 8 pm, weekends 9 am to 5 pm and public holidays 10 am to 3 pm. All consultations are bulk billed. Several doctors on our team list children’s health among their interests, including Dr Arezoo Mirzaei, Dr Farzana Yasmin and Dr Tina Dolatabadizadeh, and you can read more about our paediatric health care. You can book online through HealthEngine or call (03) 8731 1330. Outside our hours, call 13 SICK (13 7425) for an after-hours doctor.
When to call 000 or go to hospital
Some signs cannot wait for a GP appointment. Call 000 for an ambulance if your baby is struggling to breathe, their breathing is irregular or they pause between breaths, their lips look blue, they are hard to wake, or their skin is pale and sweaty.
Go straight to a hospital emergency department if your baby cannot feed normally and shows signs of dehydration, such as fewer wet nappies, cool hands and feet or sunken eyes, or if they go blue in the face when they cough. A baby under 3 months with a temperature of 38°C or more also needs to go straight to the emergency department. If you are unsure which service you need, our article on GP or emergency care explains the difference.
Caring for your baby at home
There is no medicine that cures bronchiolitis, and healthdirect notes that antibiotics do not work against RSV because it is a virus. Most cases of RSV in babies are managed at home after seeing a doctor. To help your baby in the meantime:
- offer smaller feeds more often, whether breastfeeding or formula feeding, to prevent dehydration
- use saline nasal drops or spray to clear mucus so feeding is more comfortable
- consider paracetamol or ibuprofen if your baby seems miserable, and never give aspirin
- do not let anyone smoke or vape inside your home or around your baby
Keep watching for breathing that gets harder or feeds that drop off. If your baby gets worse, see a doctor again.
Free RSV protection in Victoria
The maternal RSV vaccine, Abrysvo, is free under the National Immunisation Program. According to the Australian Government’s RSV vaccine information, it is recommended at 28 to 36 weeks of pregnancy. The antibodies pass through the placenta and protect the baby for up to 6 months from birth. You can ask about it during your antenatal care visits, alongside the whooping cough vaccine, which is recommended between 20 and 32 weeks of every pregnancy.
Babies can also receive a free RSV antibody injection, nirsevimab (Beyfortus). Under Victoria’s infant RSV immunisation program, it is offered to infants up to 8 months whose mother did not have the RSV vaccine in pregnancy, or had it less than 2 weeks before birth, and to infants with risk conditions for severe RSV whatever their mother’s vaccination status. Aboriginal and Torres Strait Islander children and children with risk conditions can receive it from 8 months up to 24 months. Eligible newborns are given it in hospital before they go home, and the 2026 program ran from mid-March to 30 September. See our RSV vaccination page, or ask one of our GPs whether your baby is eligible.
Frequently Asked Questions
Can an adult with a cold give RSV to a baby?
Yes. RSV often causes only a runny nose or a mild cough in older children and adults, but it can cause a chest infection in a baby. RSV is very contagious, and healthdirect advises hand washing and good hygiene to help avoid passing it on.
Will my baby need antibiotics for RSV?
No. RSV is a virus, so antibiotics do not help. Treatment is about keeping your baby fed, hydrated and comfortable while watching for signs that they need more care.
How long does RSV last in babies?
Most babies are sick for 7 to 10 days, with symptoms at their worst on the second or third day. The cough can continue for up to 4 weeks. See a doctor if your baby is still sick after seven days.
Is my baby eligible for the free RSV injection?
It depends on your baby’s age, whether you had the RSV vaccine in pregnancy and how long before the birth, and whether your baby has a risk condition. Victoria’s free infant program runs for a set season, which in 2026 was mid-March to 30 September, so ask your GP what applies to your baby.
If your baby has a cough and you are unsure how they are breathing, book online through HealthEngine or call Harpley Doctors in Werribee.