See also

Fever in returned traveller
Febrile child

Key points

1. Most influenza in healthy children is self-limited and uncomplicated
2. Severe disease can occur in previously well children and children with risk factors, including chronic illness
3. In hospitalised children with risk factors or features of severe disease, antiviral treatment (oseltamivir) should be commenced empirically
4. In an unwell child, a positive PCR test for influenza does not exclude co-existing or secondary serious bacterial infection

Background

• Incubation period is 1-4 days (average 2 days)
• Hand and respiratory hygiene (eg covering the mouth when coughing) reduces transmission
• Infectious period is from 24 hours prior to onset of symptoms for 4-7 days of illness. This can be prolonged in young children or those with immunodeficiency
• PCR testing can remain positive for up to 3 weeks following an infection

Assessment

Clinical features of uncomplicated influenza

• Fever: 1/3 of children have fever without other symptoms
• Rigors or chills
• Respiratory symptoms: rhinorrhoea, sore throat, cough, croup, otitis media, sinusitis
• Headache
• Myalgia, arthralgia
• Myositis
• Lethargy, malaise
• Less common: conjunctivitis, abdominal pain, nausea and vomiting

Younger children may be

• less likely to have respiratory features
• more likely to have febrile seizures
• more likely to have gastrointestinal features
• more likely to have severe disease. See Febrile child

Clinical features of severe influenza, consider treatment (see flowchart)

• Pneumonia
• Secondary bacterial infection, especially S. aureus and S. pneumoniae
• Respiratory failure
• Neurological complications
  • Encephalopathy/encephalitis
  • Aseptic meningitis
  • Guillain-Barré syndrome
  • Cerebellar ataxia
• Rhabdomyolysis
• Myocarditis and pericarditis
• Reye syndrome (associated with aspirin use)

Risk factors for severe disease, consider treatment (see flowchart)

• Severe chronic disease, particularly: neurological, respiratory, cardiac, haematological (including sickle cell disease), hepatic, chronic kidney disease, diabetes, obesity >95^th centile
• Genetic syndrome eg trisomy 21
• Neuromuscular disease
• Premature infants <37/40
• Immunosuppression
• Pregnancy
• On long term aspirin

Management

Immunisation status does not affect the management of children with suspected influenza

Investigations

• Children with a mild flu-like illness do not require testing to confirm the causative virus
• Consider testing where confirmation is likely to influence treatment decisions (eg cohorting on inpatient ward, directing therapy in high-risk children)
• Detection of influenza is by rapid antigen testing (RAT) obtained from appropriate nasal swab or PCR testing from appropriate respiratory specimen (nasal or throat swab or nasopharyngeal aspirate)

Treatment

Supportive care as required eg hydration support, analgesia and respiratory support

Admitted children should be isolated (or cohorted, depending on local infection control procedure)

Antiviral treatment

• Oseltamivir, zanamivir, baloxavir, and peramivir (IV) are neuraminidase or CAP inhibitors that reduce influenza virus replication
• Oseltamivir is usually first line therapy (oral or nasogastric)
• Treatment may have a modest effect in terms of reducing duration of symptoms (1 day on average) and may prevent more severe disease
• Treatment is most effective if started within 48 hours of onset of illness for significant illness or higher risk children
• There may be some clinical benefit up to 7 days
• Neuraminidase inhibitors have no role in treating other viral infections

Oseltamivir

• Oral capsule 30 mg, 45 mg, 75 mg or oral suspension 6 mg/mL
• Capsule contents may be dissolved in water (for use immediately)
• Side effects
  • headache
  • nausea and vomiting (reduce by giving with food), twice as likely to have vomiting (4-8% of unwell children)
• Seek advice for use in renal impairment

Prophylaxis of contacts

After significant exposure (within 1 metre for >15 minutes without personal protective equipment), oseltamivir prophylaxis is recommended for children and family members if

• personal risk factors
• household contacts have risk factors
• household contacts are:
  • aged ≥65 years
  • women who are pregnant or within 2 weeks after delivery

Oseltamivir dosage

*doses based on AMH and AAP

Peramivir

• Seek specialist advice, for inpatient use only
• Only in children over 2 years
• IV preparation: used when enteral route not appropriate

Consider consultation with local paediatric team when

Child has suspected influenza and risk factors for severe disease

Consider transfer when

• Child requiring care beyond the comfort level of the local hospital
• Child has severe disease

For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services

Consider discharge when

Child is well and education to parent/carers has been provided to parents/carers regarding monitoring for complications

Consider referral to community follow-up services for early clinical review as appropriate for your local region, ie community nursing, hospital in the home, virtual emergency department, or general practice

Parent information

Influenza (Victoria)
Influenza (NSW)
Influenza (QLD)
Influenza (SA)
Influenza Vaccination (WA)

Additional information

Influenza vaccine

• The best available preventative measure against influenza
• Recommended for all people aged >6 months annually
  • Strongly recommended and funded for children ≥6 months and <5 years
  • Strongly recommended and funded for all children with Aboriginal or Torres Strait Islander background, children with risk factors for severe influenza and pregnant women
• More information is available from the Australian Immunisation Handbook and the ATAGI annual position statement.

Last updated January 2026