RSV: What to Watch in the First Year

Respiratory syncytial virus is so common that nearly every child has had it by two. For most it is a heavy cold. For a small group, particularly babies under six months and those born prematurely or with heart or lung conditions, it causes bronchiolitis, which can be serious.

How it usually goes

Days one to three look like a cold: runny nose, mild cough, low fever. Days three to five are often the worst, when the cough deepens and breathing becomes noisier. A wheeze or crackle, a chest that pulls in below the ribs, and a breathing rate that looks fast are the features of bronchiolitis, and they usually peak around day four or five before slowly improving over a week or more. The cough can linger for three weeks and is not a sign of ongoing infection.

• Fast or laboured breathing, with ribs or neck pulling in, needs a same-day review.
• Pausing in breathing, or lips looking blue or grey, is an emergency.
• Feeding less than half of usual, or fewer wet nappies, needs assessment.
• Keep feeds smaller and more frequent when the nose is blocked.

What helps at home

There is no treatment that shortens bronchiolitis, so care is about feeding and breathing. Smaller, more frequent feeds help, because a blocked nose makes long feeds exhausting. Saline drops before feeds can clear the nose. Keep the room humid and free of smoke, which makes everything worse. Paracetamol at a weight-based dose can reduce fever and discomfort, but fever-reducing medicine does not change the illness. Antibiotics do not help, because it is a virus.

Ask about prevention if your baby is in a higher-risk group. There are monoclonal antibody injections available for infants at higher risk of severe RSV, given either seasonally or at birth depending on the country, and vaccination in pregnancy protects newborns in the first months. If your baby is under three months and developing a cough with fast breathing, do not wait until morning to call.