What is the recommended management for influenza?

Influenza Management

Antiviral Treatment: When and Who to Treat

Start oseltamivir 75 mg orally twice daily for 5 days immediately for any hospitalized patient with suspected or confirmed influenza, any patient with severe/complicated/progressive illness, and all high-risk patients, regardless of vaccination status or timing of presentation. 1, 2, 3

Immediate Treatment Indications (Start Antivirals NOW)

• Any hospitalized patient with suspected or confirmed influenza, regardless of symptom duration 1, 2
• Severe, complicated, or progressive illness attributable to influenza 1, 2
• High-risk patients including those with asthma, diabetes, immunosuppression, chronic cardiac/pulmonary disease, neurologic disorders, pregnancy, age <2 years or >65 years 1, 4

Outpatient Treatment for Previously Healthy Patients

• Treat within 48 hours of symptom onset if the patient meets ALL three criteria: acute influenza-like illness, fever >38°C (>38.5°C in children), and symptomatic for ≤48 hours 2, 5
• Maximum benefit occurs when started within 24 hours of symptom onset 2, 6
• Treatment reduces illness duration by approximately 24 hours, decreases hospitalization rates, reduces antibiotic use, and hastens return to normal activity 2, 7

Critical Timing Considerations

Do not delay antiviral treatment while awaiting laboratory confirmation—clinical diagnosis is sufficient, and early treatment provides maximum benefit. 2 Rapid antigen tests have low sensitivity and negative results should never be used to rule out influenza or guide treatment decisions 1. For high-risk and hospitalized patients, consider treatment even beyond 48 hours of symptom onset, as observational studies suggest benefit in these populations 1, 4.

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Antiviral Dosing

Adults and Adolescents (≥13 years)

• Treatment: Oseltamivir 75 mg orally twice daily for 5 days 3
• Prophylaxis: Oseltamivir 75 mg orally once daily for at least 10 days post-exposure or up to 6 weeks during community outbreak 3

Pediatric Patients (Weight-Based Dosing)

• Age 2 weeks to <1 year: 3 mg/kg twice daily for treatment (prophylaxis not approved) 3
• Age 1-12 years, ≤15 kg: 30 mg twice daily (treatment) or 30 mg once daily (prophylaxis) 3
• Age 1-12 years, 15.1-23 kg: 45 mg twice daily (treatment) or 45 mg once daily (prophylaxis) 3
• Age 1-12 years, 23.1-40 kg: 60 mg twice daily (treatment) or 60 mg once daily (prophylaxis) 3
• Age 1-12 years, >40 kg: 75 mg twice daily (treatment) or 75 mg once daily (prophylaxis) 3

Renal Impairment Adjustments

• CrCl >60 mL/min: No adjustment needed 3
• CrCl 30-60 mL/min: 30 mg twice daily for treatment, 30 mg once daily for prophylaxis 3
• CrCl 10-30 mL/min: 30 mg once daily for treatment, 30 mg every other day for prophylaxis 3
• ESRD on hemodialysis: 30 mg immediately, then 30 mg after each hemodialysis cycle 3

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Special Populations and Contraindications

Patients with Asthma or Chronic Lung Disease

Use oseltamivir exclusively—zanamivir is absolutely contraindicated in patients with asthma or COPD due to risk of fatal bronchospasm. 8 This contraindication applies regardless of disease severity 8.

Pregnancy and Postpartum

• Pregnant women should receive inactivated influenza vaccine at any time during pregnancy 1
• Oseltamivir is safe and should be used for treatment when indicated 1
• Women in the postpartum period who did not receive vaccination during pregnancy should receive vaccine before hospital discharge 1
• Influenza vaccination during breastfeeding is safe for mothers and infants 1

Egg Allergy

• Children with egg allergy can receive influenza vaccine (IIV or LAIV) without any additional precautions beyond those recommended for all vaccines 1

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Antibiotic Management: A Stratified Approach

Uncomplicated Influenza Without Pneumonia

Previously healthy adults with acute bronchitis complicating influenza do NOT routinely require antibiotics in the absence of pneumonia. 1, 2, 5

Consider antibiotics only if:

• Worsening symptoms develop (recrudescent fever or increasing dyspnea) 1, 5
• Patient is at high risk of complications AND has lower respiratory tract features 1, 2, 5

Non-Severe Influenza-Related Pneumonia

First-line oral therapy: co-amoxiclav or tetracycline 1, 5

• Alternative: macrolide (clarithromycin or erythromycin) or fluoroquinolone with pneumococcal and staphylococcal activity (levofloxacin or moxifloxacin) for penicillin-intolerant patients 1, 5
• Administer antibiotics within 4 hours of hospital admission 1, 2

Severe Influenza-Related Pneumonia

Immediate parenteral combination therapy is required upon diagnosis: 1, 2, 5

• Preferred regimen: IV co-amoxiclav or 2nd/3rd generation cephalosporin (cefuroxime or cefotaxime) PLUS macrolide (clarithromycin or erythromycin) 1, 5
• Alternative: Fluoroquinolone with enhanced pneumococcal activity (levofloxacin) PLUS broad-spectrum beta-lactamase stable antibiotic or macrolide 1
• Must cover S. aureus in addition to typical community-acquired pneumonia pathogens 2, 5

Antibiotic Duration and Route Switching

• Switch from IV to oral when clinical improvement occurs, temperature normal for 24 hours, and oral route feasible 1, 5
• Duration: 7 days for non-severe, uncomplicated pneumonia; 10 days for severe, microbiologically undefined pneumonia; 14-21 days for confirmed/suspected S. aureus or Gram-negative pneumonia 1, 5

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Chemoprophylaxis Indications

Antiviral chemoprophylaxis is recommended after known or suspected influenza exposure in these situations: 1

• Children at high risk of complications for whom influenza vaccine is contraindicated 1
• High-risk children during the 2 weeks after influenza vaccination, before optimal immunity is achieved 1
• Unvaccinated family members or healthcare personnel with ongoing close exposure to unvaccinated high-risk children or unvaccinated infants/toddlers <24 months 1
• Immunocompromised patients may continue prophylaxis for up to 12 weeks during community outbreak 3

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Critical Pitfalls to Avoid

• Never delay antiviral treatment while awaiting laboratory confirmation—clinical diagnosis is sufficient 2
• Never use aspirin in children with influenza due to risk of Reye syndrome 2
• Never prescribe zanamivir to patients with any underlying airways disease (asthma, COPD), regardless of severity 8
• Never withhold oseltamivir from high-risk or hospitalized patients even if presenting beyond 48 hours, as they may still benefit significantly 1, 4
• Never rely on negative rapid antigen tests to rule out influenza or guide treatment decisions—they have low sensitivity 1
• Always remember to cover S. aureus when treating influenza-related pneumonia with antibiotics 2, 5