What is the next treatment step for a patient with a viral panel positive for influenza?

Treatment for Influenza-Positive Patient

Start oseltamivir (Tamiflu) 75 mg orally twice daily for 5 days immediately if the patient is within 48 hours of symptom onset, has fever >38°C, and presents with acute influenza-like illness. 1, 2

Immediate Antiviral Treatment Decision

Oseltamivir is indicated if ALL of the following criteria are met:

• Acute influenza-like illness (fever, cough, myalgias, malaise) 1
• Fever >38°C in adults (>38.5°C in children) 1
• Symptomatic for ≤48 hours 1, 2

Dosing by weight/age:

• Adults and children >24 kg: 75 mg twice daily for 5 days 1, 3
• Children 15-23 kg: 45 mg twice daily for 5 days 1
• Children <15 kg: 30 mg twice daily for 5 days 1
• Reduce dose by 50% (75 mg once daily) if creatinine clearance <30 mL/min 1, 3

Key benefit: Oseltamivir reduces illness duration by approximately 24 hours, decreases hospitalization rates, and reduces secondary complications when started early. 1, 2, 4 The earlier treatment begins, the greater the benefit—starting within 12 hours provides an additional 74.6 hours of symptom reduction compared to starting at 48 hours. 5

Special Circumstances for Antiviral Use

Consider oseltamivir even outside standard criteria if:

• Patient is hospitalized with severe illness, regardless of symptom duration 1, 2
• Patient is immunocompromised 1
• Patient cannot mount adequate febrile response (elderly, immunocompromised) despite lack of documented fever 1
• Patient is at high risk for complications (chronic respiratory disease, cardiac disease, diabetes, age ≥65 years, pregnancy) 1, 2

Antibiotic Decision Algorithm

Do NOT start antibiotics if:

• Previously well patient with uncomplicated influenza (no pneumonia) 1, 6

CONSIDER antibiotics if:

• Previously well patient develops worsening symptoms: recrudescent fever or increasing dyspnea 1
• Patient at high risk of complications with lower respiratory tract features 1

START antibiotics immediately if:

• Clinical or radiographic evidence of pneumonia 1

Antibiotic Selection for Pneumonia

For non-severe pneumonia (oral therapy):

• First choice: Co-amoxiclav OR doxycycline 1
• Alternative (if penicillin allergy): Clarithromycin or erythromycin 1

For severe pneumonia (parenteral therapy):

• IV co-amoxiclav or cefuroxime/cefotaxime PLUS clarithromycin or erythromycin 1
• Duration: 7 days for uncomplicated pneumonia, 10 days for severe pneumonia 1

Hospital Referral Criteria

Assess CRB-65 score (1 point each):

• Confusion 1
• Respiratory rate ≥30/min 1
• Blood pressure: systolic <90 mmHg or diastolic ≤60 mmHg 1
• Age ≥65 years 1

Referral decisions:

• CRB-65 score 0-1: Consider home treatment 1
• CRB-65 score 2: Consider short inpatient stay or hospital-supervised outpatient management 1
• CRB-65 score ≥3: Urgent hospital admission 1
• Bilateral chest signs: Hospital referral regardless of score 1

Monitoring and Supportive Care

Assess and provide:

• Oxygen therapy to maintain pO2 >8 kPa or SaO2 >92% 1
• IV fluids if needed 1
• Antipyretics (avoid aspirin in children due to Reye's syndrome risk) 1

Monitor vital signs at least twice daily:

• Temperature, respiratory rate, pulse, blood pressure, mental status, oxygen saturation 1

Common Pitfalls to Avoid

• Do not delay oseltamivir waiting for laboratory confirmation if clinical suspicion is high and patient meets treatment criteria 2, 7
• Do not prescribe antibiotics reflexively for uncomplicated influenza without evidence of bacterial superinfection 1, 6
• Do not dismiss treatment in patients presenting >48 hours if severely ill or hospitalized 1, 2
• Most common oseltamivir side effect is nausea (10%), which can be managed by taking with food 1, 5