Flu, COVID-19 and RSV in Children: Antivirals, Prophylaxis, Nirsevimab

About this tool

This tool helps clinicians manage the three main winter respiratory viruses in children. For influenza it shows who should get antivirals right away (hospitalized, severe or progressive illness, and high-risk children, including all children under 2 years), and gives oseltamivir doses for preterm infants by postmenstrual age, term infants, and older children by weight band, with baloxavir, inhaled zanamivir and IV peramivir where they fit.

It also covers influenza post-exposure prophylaxis, COVID-19 treatment by severity (supportive care for most, nirmatrelvir-ritonavir for high-risk adolescents 12 years and older and 40 kg or more, remdesivir and dexamethasone in hospital), and RSV prevention: nirsevimab or clesrovimab for infants under 8 months in their first season unless the mother was vaccinated 14 days or more before birth, and nirsevimab 200 mg for high-risk children in their second season.

Each result includes isolation precautions and return-to-school rules: fever-free for 24 hours without fever medicine and symptoms improving overall. RSV illness itself is treated with supportive care; the bronchiolitis tool covers that in detail. Where pediatric data are limited, the tool says to consult pediatric infectious diseases.

Common questions

Which children with influenza need antiviral treatment?

Treat as soon as possible, regardless of how many days they have been sick, any child who is hospitalized, has severe, complicated or progressive illness, or is at high risk, including all children under 2 years and those with chronic medical conditions. Otherwise healthy children may be treated if seen within 48 hours.

What is the oseltamivir dose for children?

Term infants under 1 year: 3 mg/kg/dose twice daily. One year and older: 30 mg (15 kg or less), 45 mg (over 15–23 kg), 60 mg (over 23–40 kg) or 75 mg (over 40 kg) twice daily for 5 days. Prophylaxis uses the same dose once daily for 7 days.

Who should get nirsevimab?

All infants under 8 months born during or entering their first RSV season, unless the mother received RSV vaccine at 32–36 weeks 14 days or more before birth: 50 mg if under 5 kg, 100 mg if 5 kg or more. High-risk children 8–19 months get 200 mg before their second season. Clesrovimab 105 mg is an alternative in the first season.

When can a child with flu or COVID-19 go back to school?

When fever-free for 24 hours without fever medicine and symptoms are improving overall, followed by 5 days of extra precautions such as masking and hand hygiene.

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