Treatment algorithm
Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer
Primary options
oseltamivir: children ≥3 months of age: 3 mg/kg orally twice daily for 5-10 days; children >1 year of age and ≤15 kg body weight: 30 mg orally twice daily for 5-10 days; children >15-23 kg body weight: 45 mg orally twice daily for 5-10 days; children >23-40 kg body weight: 60 mg orally twice daily for 5-10 days; children >40 kg body weight and adults: 75 mg orally twice daily for 5-10 days
MoreSecondary options
zanamivir: children ≥5 years of age and adults: 10 mg (2 puffs) inhaled twice daily for 5-10 days
MoreThe decision to use antiviral chemoprophylaxis should be considered on a case-by-case basis and guided by assessment of highly pathogenic avian influenza (HPAI) H5N1 virus exposure and subsequent risk of developing infection. No prospective clinical trials exist to guide World Health Organization (WHO) chemoprophylaxis recommendations. Guidelines are based on observational data for HPAI H5N1 cases and their contacts, and studies of seasonal influenza.[87]
Close observation and postexposure oseltamivir or zanamivir chemoprophylaxis is recommended for healthcare workers after unprotected close exposure to a symptomatic, suspected, or confirmed HPAI H5N1 case (within 2 m) in the healthcare setting, as well as for household members and close contacts of a person with suspected or confirmed HPAI H5N1 virus infection. Local or national public health departments should be contacted for guidance.
Oseltamivir is the preferred option in pregnant women.[98]
Children may experience unique cutaneous, behavioral, and neurologic adverse events with neuraminidase inhibitors; therefore, extra caution should be used in this population.
If postexposure antiviral chemoprophylaxis is administered, it should be given twice daily (treatment dosing frequency) rather than once daily because of potential that HPAI H5N1 virus infection may have already occurred.[88]
If exposure was time-limited and not ongoing, chemoprophylaxis is recommended for 5 days from the last known exposure. If exposure is likely to be ongoing (e.g., household setting), 10 days is recommended.[88]
Recommended doses are based on guidelines from the Centers for Disease Control and Prevention (CDC).[98]
Primary options
oseltamivir: children <14 days of age: consult specialist for guidance on dose; children 14 days to 1 year of age: 3 mg/kg orally twice daily for 5 days; children >1 year of age and ≤15 kg body weight: 30 mg orally twice daily for 5 days; children >15-23 kg body weight: 45 mg orally twice daily for 5 days; children >23-40 kg body weight: 60 mg orally twice daily for 5 days; children >40 kg body weight and adults: 75 mg orally twice daily for 5 days
MoreSecondary options
zanamivir: children ≥7 years of age and adults: 10 mg (2 puffs) inhaled twice daily for 5 days
When highly pathogenic avian influenza (HPAI) H5N1 is highly suspected, isolating the patient and treating early with empiric neuraminidase inhibitor according to existing guidelines while waiting for the results of specific laboratory tests is appropriate. It is important to note that HPAI A (H5N1) virus infection of humans appears to be very rare, and physicians must consider alternative diagnoses when evaluating patients with suspected HPAI H5N1 virus infection.
Oral or enterically-administered oseltamivir is the recommended antiviral medication treatment.[17][22][38][59] Inhaled zanamivir might be used as an alternative regimen in nonintubated patients.[86]
Oseltamivir is the preferred option in pregnant women.[98]
Children may experience unique cutaneous, behavioral, and neurologic adverse events with neuraminidase inhibitors; therefore, extra caution should be used in this population.
Combination oseltamivir and zanamivir treatment is not recommended because of the potential for antagonism.[96]
Recommended doses are based on guidelines from the Centers for Disease Control and Prevention (CDC).[98]
Treatment recommended for ALL patients in selected patient group
Given the potential infectiousness and virulence of highly pathogenic avian influenza (HPAI) A (H5N1) virus, enhanced infection control precautions are recommended. All infection control strategies include standard hand hygiene precautions. There may be slight infection control recommendation differences between the WHO[97] and some national public health organizations; therefore, if HPAI H5N1 is considered in a patient, it is recommended that clinicians consult national infection control guidelines.
Most patients admitted to the hospital with highly pathogenic avian influenza (HPAI) H5N1 virus infection have had rapidly progressive pneumonia leading to ARDS and multiorgan failure.[17] Patients with early recognition of disease and initiation of antiviral and supportive therapies may have improved clinical outcomes.[100][101]
While there is no standardized approach for the clinical management of humans with HPAI H5N1 virus infection, the WHO recommends that supportive care follow published evidence-based guidelines for the clinical syndrome present (e.g., septic shock, respiratory failure, and ARDS).[17][90] According to the WHO, patients who have severe or progressive clinical illness, including viral pneumonitis, respiratory failure, and ARDS due to influenza virus infection, should not be given systemic corticosteroids unless indicated for other reasons (e.g., adrenal insufficiency, refractory septic shock) or as part of an approved research protocol.[86]
Treatment recommended for ALL patients in selected patient group
Primary options
oseltamivir: children <14 days of age: consult specialist for guidance on dose; children 14 days to 1 year of age: 3 mg/kg orally twice daily for 5 days; children >1 year of age and ≤15 kg body weight: 30 mg orally twice daily for 5 days; children >15-23 kg body weight: 45 mg orally twice daily for 5 days; children >23-40 kg body weight: 60 mg orally twice daily for 5 days; children >40 kg body weight and adults: 75 mg orally twice daily for 5 days
MoreSecondary options
zanamivir: children ≥7 years of age and adults: 10 mg (2 puffs) inhaled twice daily for 5 days
Oral or enterically-administered oseltamivir is the recommended antiviral medication treatment.[17][22][38][59] Inhaled zanamivir might be used as an alternative regimen in nonintubated patients.[86]
Oseltamivir is the preferred option in pregnant women.[98]
Children may experience unique cutaneous, behavioral, and neurologic adverse events with neuraminidase inhibitors; therefore, extra caution should be used in this population.
Modified regimens with higher doses of oseltamivir and longer duration of treatment may be considered in a case-by-case basis, but there are no available clinical trial data to inform recommendations.[86]
Oseltamivir has been shown to be adequately absorbed following nasogastric administration to mechanically ventilated adults with severe highly pathogenic avian influenza (HPAI) H5N1 disease.[102]
Combination oseltamivir and zanamivir treatment is not recommended because of the potential for antagonism.[96]
Recommended doses are based on guidelines from the Centers for Disease Control and Prevention (CDC).[98]
Treatment recommended for ALL patients in selected patient group
Given the potential infectiousness and virulence of highly pathogenic avian influenza (HPAI) A (H5N1) virus, enhanced infection control precautions are recommended. All infection control strategies include standard hand hygiene precautions. There may be slight infection control recommendation differences between the WHO[97] and some national public health organizations; therefore, if HPAI H5N1 is considered in a patient, it is recommended that clinicians consult national infection control guidelines.
Treatment recommended for SOME patients in selected patient group
Primary options
amantadine: see local, national, or WHO guidelines for dosing recommendations
MoreOR
rimantadine: see local, national, or WHO guidelines for dosing recommendations
MoreGiving M2 inhibitors (amantadine or rimantadine) alone as a first-line therapy is not recommended.
According to the WHO, a combination of a neuraminidase inhibitor and an M2 inhibitor should be considered if local surveillance data show that the highly pathogenic avian influenza (HPAI) H5N1 virus is known or likely to be susceptible, but this should be done only in the context of research or prospective data collection.[87]
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