What is the treatment for Influenza A (H5N1) virus infection, also known as Avian Influenza (AI), in humans?

From the Guidelines

Treatment of Avian Influenza (H5N1) in humans should be initiated promptly with oseltamivir (Tamiflu) at a dose of 75mg twice daily for 5 days, as recommended by the WHO rapid advice guidelines 1. The choice of antiviral medication is crucial in managing H5N1 infection, and oseltamivir is the preferred option due to its effectiveness in reducing mortality and duration of hospitalization 1.

• The recommended dose and duration of treatment vary by age group, with weight-adjusted doses for children and a fixed dose of 75mg twice daily for adults aged 13-64 years 1.
• Zanamivir (Relenza) is an alternative option, but its use is limited to patients aged 7 years and above, with a recommended dose of 10mg (two inhalations) twice daily for 5 days 1.
• Amantadine and rimantadine are also options, but their use is limited due to concerns about resistance and side effects 1. Key considerations in managing H5N1 infection include:
• Early treatment initiation, ideally within 48 hours of symptom onset
• Supportive care, including oxygen therapy, mechanical ventilation, and fluid management
• Isolation to prevent transmission to others
• Monitoring for secondary bacterial infections and treatment with appropriate antibiotics The WHO guidelines emphasize the importance of prompt treatment and supportive care in reducing morbidity and mortality associated with H5N1 infection 1.

From the FDA Drug Label

Oseltamivir phosphate for oral suspension is indicated for the treatment of acute, uncomplicated illness due to influenza A and B infection in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. The treatment for Influenza A (H5N1) virus infection, also known as Avian Influenza (AI), in humans is oseltamivir phosphate for oral suspension.

• The recommended treatment duration is not explicitly stated for Influenza A (H5N1) in the provided drug labels, but for acute, uncomplicated illness due to influenza A and B infection, the treatment duration is 5 days as mentioned in the clinical studies section of the drug label 2.
• Key points to consider when using oseltamivir phosphate for oral suspension:
  • It is not a substitute for early influenza vaccination on an annual basis as recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices.
  • Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use oseltamivir phosphate for oral suspension 2.

From the Research

Treatment Options for Influenza A (H5N1) Virus Infection

• The treatment for Influenza A (H5N1) virus infection, also known as Avian Influenza (AI), in humans is primarily supportive care with the addition of antiviral medications 3.
• Neuraminidase inhibitors are the mainstay of the avian influenza treatment and include oseltamivir, peramivir, and zanamivir 4.
• Baloxavir marboxil is a cap-dependent endonuclease inhibitor that can also be used to treat avian influenza 4.
• Chemoprophylaxis against avian influenza following a suspected exposure should be started as soon as possible or no later than 48 hours, and it is recommended to be continued for 7 days 4.

Antiviral Medications

• Neuraminidase inhibitors (NAIs) are the treatment of choice for influenza due to widespread resistance to the adamantanes 5.
• NAIs are efficacious for the treatment of influenza in ambulatory patients with mild illness, when initiated within 48 hours of symptom onset 5.
• Early treatment with NAIs has been shown to reduce otitis media in children, and lower respiratory tract complications, resulting in antibiotic therapy, in adults 5.
• Oseltamivir-resistant virus has been widely reported but is predominantly an issue in H1N1 seasonal influenza 5.
• Zanamivir-resistant influenza virus is rare, and inhaled or intravenous (IV) zanamivir is the treatment of choice in proven or suspected oseltamivir-resistant virus 5.

Timing of Treatment

• The benefit of treatment is greatest when antiviral therapy is started within 24 hours of symptom onset 6.
• Treatment with NAIs should be initiated as soon as possible in patients at high-risk of influenza-related complications, with suspected or proven influenza, hospitalised patients and patients with severe or progressive disease 5.
• NAIs can be considered in previously healthy patients when therapy can be initiated within 48 hours of symptom onset 5.
• Several observational studies suggest therapeutic benefit beyond 48 hours, in hospitalised patients, severe disease, and patients at high risk of complications, including pregnant women 5.