Postexposure antiviral prophylaxis for influenza

The annual influenza vaccination is the most important measure to prevent influenza – for comprehensive advice, see the Australian Immunisation Handbook.

Consider antiviral prophylaxis as part of outbreak management for patients in hospital or residential care facilities1, and healthcare workers.

Consider influenza antiviral prophylaxis for people at high risk of severe illness or complications who have been exposed to influenza in the past 48 hours (but do not have infection), and who:

  • have not received an annual influenza vaccine for the current season
  • received the annual influenza vaccine within the previous 2 weeks
  • might not respond to vaccination (eg patients with immune compromise)
  • live in a community in which the circulating strain of influenza is not covered by the annual vaccine.

If antiviral prophylaxis for influenza is indicated, useWorld Health Organization (WHO), 2024Uyeki, 2018:

1oseltamivir orally, daily for 10 days. For dosage adjustment in adults with kidney impairment, see oseltamivir dosage adjustment oseltamivir oseltamivir oseltamivir

adult: 75 mg

child 3 months to less than 1 year2: 3 mg/kg

child 1 year or older and less than 15 kg: 30 mg

child 1 year or older and 15 to less than 23 kg: 45 mg

child 1 year or older and 23 to 40 kg: 60 mg

child 1 year or older and more than 40 kg: 75 mg

OR

1baloxavir (adult or child 12 years or older3) orally, as a single doseIkematsu, 20204 baloxavir baloxavir baloxavir

40 kg to less than 80 kg: 40 mg

80 kg or more: 80 mg

OR

2zanamivir (adult and child 5 years or older) 10 mg by inhalation, daily for 10 days. zanamivir zanamivirzanamivir

For information about primary prophylaxis of influenza in adults with immune compromise in a high-risk unit (eg haematopoietic stem cell transplant [HSCT] unit) during an outbreak, see Influenza virus prophylaxis in immunocompromised adults without HIV infection.

For detailed recommendations about prevention of influenza and avian influenza, see the Communicable Diseases Network Australia (CDNA) guidelines on influenza.

1 For advice on antiviral prophylaxis for residents of an aged-care facility, see the National Guidelines for the Prevention, Control and Public Health Management of Outbreaks of Acute Respiratory Infection (including COVID-19 and Influenza) in Residential Care Facilities.Return
2 For children younger than 3 months, seek expert advice on oseltamivir for prophylaxis for influenza.Return
3 For children younger than 12 years, seek expert advice on baloxavir for prophylaxis for influenza.Return
4 At the time of writing, baloxavir is newly registered for use in Australia. Monitor patients and report any adverse effects through the Therapeutic Goods Administration (TGA) website.Return