What is the treatment for influenza A?

Treatment of Influenza A

Antiviral treatment with a neuraminidase inhibitor (NAI) should be started as soon as possible for patients with suspected or confirmed influenza A, with oral oseltamivir being the preferred first-line agent for most patients. 1, 2

Patient Selection for Antiviral Treatment

• Antiviral treatment should be initiated for all patients with suspected or confirmed influenza who are: 1

  • Hospitalized with influenza, regardless of illness duration 1
  • Experiencing severe or progressive illness 1
  • At high risk of complications (those with chronic medical conditions or immunocompromised) 1
  • Children younger than 2 years or adults ≥65 years 1
  • Pregnant women and those within 2 weeks postpartum 1

• Antiviral treatment can be considered for otherwise healthy individuals not at high risk of complications 1, 3

First-Line Treatment Options

• Oral oseltamivir (Tamiflu): 75 mg twice daily for 5 days for adults and adolescents over 13 years 1, 4

  • Pediatric dosing is weight-based for children 2 weeks through 12 years of age 4
  • Can be taken with food to enhance tolerability 2
  • Effective against both influenza A and B viruses 2, 4

• Inhaled zanamivir (Relenza): 10 mg (two 5 mg inhalations) twice daily for 5 days 1, 5

  • Not recommended for patients with underlying airways disease due to risk of bronchospasm 5
  • Approved for patients 7 years and older 5

• Intravenous peramivir: Single dose option for patients unable to take oral or inhaled medications 1

Timing of Treatment

• Treatment should be initiated as soon as possible after symptom onset, ideally within 48 hours 1, 2, 4
• Early treatment (within 24-48 hours) provides the greatest benefit in reducing symptom duration and severity 2, 3
• Treatment should not be withheld if beyond the 48-hour window, especially in severely ill patients 3

Duration of Treatment

• Standard treatment duration is 5 days for uncomplicated influenza in otherwise healthy patients 1
• Consider longer treatment duration for: 1
  • Immunocompromised patients 1
  • Patients requiring hospitalization for severe lower respiratory tract disease 1
  • Patients with evidence of persistent viral replication 1

Management of Complications

• Investigate and empirically treat bacterial coinfection in patients with: 1

  • Severe initial presentation (extensive pneumonia, respiratory failure, hypotension, fever) 1
  • Clinical deterioration after initial improvement 1
  • Failure to improve after 3-5 days of antiviral treatment 1

• Consider influenza antiviral resistance testing for: 1

  • Patients who develop influenza while on or after NAI chemoprophylaxis 1
  • Immunocompromised patients with persistent viral replication despite treatment 1
  • Patients who received subtherapeutic antiviral dosing 1
  • Patients with severe influenza who don't improve with treatment 1

What NOT to Use

• Do not use combination neuraminidase inhibitor therapy 1
• Do not routinely use higher doses of FDA-approved NAI drugs 1
• Avoid corticosteroid adjunctive therapy unless clinically indicated for other reasons 1
• Do not routinely administer immunoglobulin preparations for treatment 1
• Older antiviral agents (amantadine and rimantadine) are no longer recommended due to widespread resistance 1

Special Considerations

• For critically ill patients, some experts suggest higher oseltamivir dosing (e.g., 150 mg twice daily) 1
• For patients with renal impairment, dose adjustment of oseltamivir is required 4
• Empiric treatment should be considered during influenza season for high-risk patients presenting with typical symptoms 3, 6
• Antiviral treatment is not a substitute for influenza vaccination, which remains the cornerstone for prevention 3, 4

Common Pitfalls

• Delaying treatment while awaiting laboratory confirmation in high-risk patients 3, 7
• Underutilizing antivirals in high-risk outpatients (only 37% of high-risk patients with confirmed influenza receive appropriate treatment) 6
• Failing to recognize influenza in afebrile patients (25% of high-risk patients with influenza may be afebrile) 6
• Not considering influenza outside of typical influenza season 7