What are the guidelines for managing influenza?

Guidelines for Managing Influenza

Antiviral medications should be started as soon as possible within 48 hours of symptom onset in patients with confirmed or suspected influenza, particularly for those at high risk of complications. 1

Diagnosis

• Consider influenza diagnosis during influenza season in patients with fever and acute respiratory symptoms, regardless of vaccination status 2, 3
• Laboratory testing is recommended for hospitalized patients and those where confirmation would change management decisions 1
• Preferred diagnostic tests include rapid molecular assays (nucleic acid amplification tests) over rapid influenza diagnostic tests (RIDTs) for improved detection 1
• Nasopharyngeal specimens (optimal) or mid-turbinate nasal swabs should be collected rather than throat swabs 1
• For patients on mechanical ventilation, endotracheal aspirate or bronchoalveolar lavage fluid specimens should be collected 1

Antiviral Treatment

Indications for Treatment

• Hospitalized patients with confirmed or suspected influenza 2
• Outpatients at high risk of complications (including those with chronic medical conditions, immunocompromised patients) 3
• Children younger than 2 years and adults ≥65 years 3
• Pregnant women and those within 2 weeks postpartum 3
• Patients with severe or progressive illness 3
• Otherwise healthy individuals who present within 48 hours of symptom onset may be considered for treatment 2, 3

Recommended Antiviral Medications

• Oseltamivir (Tamiflu) is the preferred first-line treatment 1, 3:

  • Adults and children >24kg: 75 mg twice daily for 5 days
  • Children 15-23 kg: 45 mg twice daily for 5 days
  • Children ≤15 kg: 30 mg twice daily for 5 days
  • Dose should be reduced by 50% if creatinine clearance is less than 30 ml/min 2

• Zanamivir (Relenza) is an alternative for patients who cannot tolerate oseltamivir 3:

  • 10 mg (two 5-mg inhalations) twice daily for 5 days
  • Not recommended for individuals with underlying airways disease 4

• Peramivir is an option for patients who cannot absorb oral medication 3

• Baloxavir is an alternative for patients ≥12 years 3

Timing and Benefits of Treatment

• Greatest benefit occurs when treatment is started within 24 hours of symptom onset 3
• Benefits include reduction of illness duration by approximately 24 hours, possible reduction in hospitalization rates, and reduction in subsequent antibiotic use 2, 5
• Hospitalized patients who are severely ill may benefit from antiviral treatment started more than 48 hours from disease onset 2

Management of Complications

Influenza Without Pneumonia

• Previously well adults with acute bronchitis complicating influenza, without pneumonia, do not routinely require antibiotics 2
• Consider antibiotics in previously well adults who develop worsening symptoms (recrudescent fever or increasing dyspnea) 2
• Patients at high risk of complications should be considered for antibiotics if lower respiratory features are present 2

Influenza-Related Pneumonia

• Non-severe pneumonia:

  • Most patients can be adequately treated with oral antibiotics 2
  • Preferred oral therapy: co-amoxiclav or a tetracycline 2
  • When oral therapy is contraindicated, use intravenous co-amoxiclav or a second/third generation cephalosporin 2

• Severe pneumonia:

  • Treat immediately with parenteral antibiotics 2
  • Preferred regimen: intravenous combination of a broad-spectrum beta-lactamase stable antibiotic (co-amoxiclav or cephalosporin) with a macrolide 2

• Antibiotics should be administered within four hours of admission for pneumonia 2

Special Considerations

• Investigate and empirically treat bacterial co-infection in patients with severe disease, clinical deterioration after initial improvement, or failure to improve after 3-5 days of antiviral treatment 3
• Patients should show clinical improvement within 48 hours of starting treatment; failure to improve should prompt clinical reassessment 3
• Consider resistance testing in immunocompromised patients with persistent viral replication or severe influenza not improving with treatment 3
• Do not administer corticosteroid adjunctive therapy for influenza treatment unless clinically indicated for other reasons 3

Prevention

• Annual influenza vaccination remains the primary preventive measure 1, 6
• Consider antiviral chemoprophylaxis for high-risk patients for whom influenza vaccine is contraindicated, or during the 2 weeks after vaccination before optimal immunity is achieved 3
• Oseltamivir (75 mg once daily) can be used for prophylaxis in high-risk individuals during local influenza activity 1
• During facility outbreaks, consider antiviral prophylaxis for all patients without influenza in the involved unit 1

Monitoring and Discharge Criteria

• Monitor temperature, respiratory rate, pulse, blood pressure, mental status, oxygen saturation in hospitalized patients 2
• Consider discharge when patients have been stable for 24 hours with: temperature <37.8°C, heart rate <100/min, respiratory rate <24/min, systolic blood pressure >90 mmHg, and oxygen saturation >90% 2