Treatment of Influenza A

Patient Selection for Antiviral Treatment

The Infectious Diseases Society of America recommends antiviral treatment for all patients with suspected or confirmed influenza who are hospitalized, experiencing severe or progressive illness, at high risk of complications, children younger than 2 years or adults ≥65 years, and pregnant women and those within 2 weeks postpartum 1
Antiviral treatment can be considered for otherwise healthy individuals not at high risk of complications, according to the Clinical Infectious Diseases guidelines 1, 3

The American College of Physicians recommends oral oseltamivir (Tamiflu) 75 mg twice daily for 5 days for adults and adolescents over 13 years, as it is effective against both influenza A and B viruses 1, 2
Inhaled zanamivir (Relenza) 10 mg (two 5 mg inhalations) twice daily for 5 days is an alternative option, but not recommended for patients with underlying airways disease due to risk of bronchospasm 1

The Centers for Disease Control and Prevention recommend initiating treatment as soon as possible after symptom onset, ideally within 48 hours, as early treatment provides the greatest benefit in reducing symptom duration and severity 1, 2
Treatment should not be withheld if beyond the 48-hour window, especially in severely ill patients, according to the Clinical Infectious Diseases guidelines 3

The Infectious Diseases Society of America recommends investigating and empirically treating bacterial coinfection in patients with severe initial presentation, clinical deterioration after initial improvement, or failure to improve after 3-5 days of antiviral treatment 1, 5
Influenza antiviral resistance testing should be considered for patients who develop influenza while on or after NAI chemoprophylaxis, immunocompromised patients with persistent viral replication despite treatment, and patients who received subtherapeutic antiviral dosing 1, 4

The American Thoracic Society recommends avoiding combination neuraminidase inhibitor therapy, higher doses of FDA-approved NAI drugs, and corticosteroid adjunctive therapy unless clinically indicated for other reasons 1, 4
Older antiviral agents (amantadine and rimantadine) are no longer recommended due to widespread resistance, according to the American Journal of Respiratory and Critical Care Medicine 6, 7