What is the best treatment for Influenza A (influenza type A)?

From the Guidelines

The best way to treat influenza A is to start antiviral treatment as soon as possible, ideally within 48 hours of symptom onset, with medications such as oseltamivir (Tamiflu) 75mg twice daily for 5 days, for adults and children with documented or suspected influenza, irrespective of influenza vaccination history, who meet certain criteria. These criteria include persons of any age who are hospitalized with influenza, outpatients of any age with severe or progressive illness, outpatients who are at high risk of complications from influenza, children younger than 2 years and adults ≥65 years, and pregnant women and those within 2 weeks postpartum 1.

Key Considerations

• Antiviral treatment should be started as soon as possible after illness onset, with the greatest benefit when started within 48 hours of influenza illness onset 1.
• High-risk individuals, including those with chronic medical conditions, immunocompromised patients, and pregnant women, should seek medical attention promptly as they may need more aggressive treatment 1.
• Supportive care, such as staying well-hydrated, getting plenty of rest, and taking acetaminophen or ibuprofen for fever and body aches, is equally important in the treatment of influenza A.
• Alternatives to oseltamivir include zanamivir (Relenza) 10mg inhaled twice daily for 5 days, peramivir (Rapivab) as a single IV dose, or baloxavir (Xofluza) as a single oral dose based on weight.

Patient Groups

• Children younger than 2 years and adults ≥65 years should receive antiviral treatment, as they are at higher risk for complications from influenza 1.
• Pregnant women and those within 2 weeks postpartum should also receive antiviral treatment, as they are at higher risk for complications from influenza 1.
• Outpatients who are at high risk of complications from influenza, including those with chronic medical conditions and immunocompromised patients, should receive antiviral treatment 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. RELENZA, an influenza virus neuraminidase inhibitor (NAI), is indicated for: Treatment of acute, uncomplicated influenza type A and B infections in patients aged 7 years and older who have been symptomatic for no more than 2 days.

The best way to treat influenza A is with oseltamivir (PO) or zanamivir (INH), as both are indicated for the treatment of acute, uncomplicated influenza A infections.

• Oseltamivir (PO) is approved for patients 2 weeks of age and older who have been symptomatic for no more than 48 hours 2.
• Zanamivir (INH) is approved for patients 7 years and older who have been symptomatic for no more than 2 days 3. Treatment should be initiated as soon as possible, as the effectiveness of these medications decreases with delayed treatment.

From the Research

Treatment Options for Influenza A

• Oseltamivir is a potent and selective inhibitor of the neuraminidase glycoprotein essential for replication of influenza A and B viruses 4.
• Studies have shown that oseltamivir reduces the duration of the disease by up to 1.5 days and the severity of illness by up to 38% compared with placebo when initiated within 36 hours of symptom onset 4, 5.
• The standard dosage of oseltamivir is 75 mg twice daily for 5 days, and it has been shown to be effective in treating influenza A in adults and children 4, 6.

Efficacy of Oseltamivir in Different Patient Populations

• Oseltamivir has been shown to be effective in treating influenza A in otherwise healthy adults, as well as in high-risk populations such as the elderly or those with chronic cardiac or respiratory disease 4.
• In children, oseltamivir has been shown to be effective in reducing the duration of fever and improving clinical outcomes 6.
• In patients with influenza B, higher-dose oseltamivir treatment (150 mg twice daily) has been shown to improve virologic response compared with standard-dose treatment (75 mg twice daily) 7.

Timing and Dosage of Oseltamivir Treatment

• Early initiation of oseltamivir treatment, within 36 hours of symptom onset, is associated with faster resolution of symptoms and improved clinical outcomes 4, 5.
• There is no significant benefit to starting oseltamivir treatment more than 48 hours after symptom onset in hospitalized general medicine patients or outpatients infected with either H1N1 or other influenza strains 8.
• Doubling the dose of oseltamivir (to 150 mg twice daily) does not confer significant survival benefit in adults hospitalized with influenza A, but may improve virologic response in influenza B patients 7, 8.