Respiratory Syncytial Virus (RSV)

Symptoms

In babies and young children

Symptoms usually start 4 to 6 days after exposure:

• runny nose and decreased appetite
• cough, sneezing, fever
• wheezing and fast breathing, often peaking around days 3 to 5
• irritability, decreased activity
• in very young babies, the only signs may be irritability, poor feeding and pauses in breathing

RSV is the most common cause of bronchiolitis, inflammation of the small airways, and a common cause of pneumonia in children under 1.

In adults

• cold symptoms: runny or stuffy nose, sore throat, cough, mild headache, fever
• in older adults or those with chronic illness: wheezing, shortness of breath, pneumonia, and flare-ups of COPD, asthma or heart failure

How RSV spreads

RSV spreads through droplets from coughs and sneezes, direct contact such as kissing a child's face, and touching contaminated surfaces then the eyes, nose or mouth. It survives on hard surfaces for hours. People are usually contagious for 3 to 8 days, but babies and people with weakened immunity can spread it for up to 4 weeks.

Who is at higher risk of severe RSV

• babies under 6 months, especially under 2 months
• premature babies
• children with chronic lung disease or congenital heart disease
• children and adults with weakened immune systems
• adults 60 and older, especially 75 and older
• adults with chronic heart or lung disease, diabetes, kidney disease or living in care homes

Diagnosis

RSV is usually diagnosed from symptoms during RSV season. A nose swab test (rapid antigen or PCR, often combined with flu and COVID-19 testing) confirms it when results would change care, for example in hospital.

Treatment

There is no routine antiviral for RSV. Care is supportive:

• fluids: offer smaller, more frequent feeds; watch wet diapers
• nasal saline and gentle suction to clear a baby's nose before feeds and sleep
• fever relief: acetaminophen (paracetamol) for babies over 2 to 3 months as advised, or ibuprofen for babies over 6 months, following weight-based dosing; no aspirin for children
• humidified air may ease congestion
• hospital care for some: oxygen, fluids through a vein or tube, and breathing support

Antibiotics do not help unless there is a bacterial complication. Asthma inhalers and steroids are not recommended for typical infant bronchiolitis.

Prevention

For infants

• maternal RSV vaccine given at 32 to 36 weeks of pregnancy during RSV season passes antibodies to the baby
• nirsevimab or clesrovimab, long-acting antibody injections, recommended for infants under 8 months entering their first RSV season if the mother was not vaccinated, and for some higher-risk toddlers in their second season

For older adults

RSV vaccines are recommended in the US for adults 75 and older, and for adults 50 to 74 at increased risk, as a single dose. Check current CDC guidance, as recommendations are updated.

Everyday measures

• wash hands often and clean frequently touched surfaces
• keep sick people away from babies
• avoid kissing babies' faces if you have a cold
• avoid smoke exposure around babies

Frequently asked questions

What are the first signs of RSV in a baby?

Early signs are a runny nose, decreased feeding and a cough, sometimes with fever. Over a few days, breathing may become fast or labored and wheezing may develop. In very young babies, irritability, poor feeding and pauses in breathing may be the only signs.

How long does RSV last?

Most RSV infections last 1 to 2 weeks. In babies, symptoms usually peak around days 3 to 5. A cough can linger for several weeks after other symptoms improve.

Is RSV dangerous for adults?

For most healthy adults, RSV is like a cold. It can be serious for adults 60 and older and those with heart or lung disease, diabetes or weakened immunity, causing pneumonia and worsening chronic conditions. Vaccination is recommended for many older adults.

How is RSV treated?

Treatment is supportive: fluids, clearing the nose, fever relief and monitoring breathing. Babies and adults with severe illness may need hospital care with oxygen and fluids. Antibiotics do not treat RSV itself.