What are the management and treatment options for a patient exposed to influenza (flu)?

Management of Influenza Exposure

For a patient exposed to influenza last week who remains asymptomatic, no treatment is indicated—only watchful waiting with instructions to return if symptoms develop. 1

Immediate Assessment

If the patient is currently asymptomatic (no fever, cough, or other influenza-like symptoms):

• No antiviral prophylaxis or treatment is warranted at this time, as exposure alone without illness does not meet criteria for intervention 1, 2
• Educate the patient to monitor for symptom development over the next 1-4 days (typical incubation period) 3
• Instruct immediate return if fever (>38°C) plus respiratory symptoms develop 1

If Symptoms Have Already Developed

Antiviral Treatment Criteria

Oseltamivir should be initiated immediately if ALL three criteria are met: 1, 2

• Acute influenza-like illness (fever, cough, myalgias, headache) 3, 4
• Fever >38°C present 1
• Symptomatic for ≤48 hours 1, 2

Dosing: Oseltamivir 75 mg orally every 12 hours for 5 days (reduce to 75 mg once daily if creatinine clearance <30 mL/min) 1, 2

Important Exceptions to the 48-Hour Rule

• Immunocompromised or very elderly patients who cannot mount adequate febrile response may still receive antivirals despite lack of documented fever 1
• Severely ill hospitalized patients may benefit from oseltamivir even if started >48 hours from symptom onset, though evidence is limited 1, 5

Antibiotic Considerations

Do NOT Give Antibiotics If:

• Previously healthy adults with uncomplicated influenza or acute bronchitis without pneumonia do not require antibiotics 1

DO Consider Antibiotics If:

High-risk patients (elderly, chronic lung/heart disease, immunocompromised) who develop lower respiratory symptoms should receive empiric antibiotics covering S. pneumoniae, S. aureus, and H. influenzae 1

Preferred regimens: 1

• Co-amoxiclav OR doxycycline (oral)
• Macrolide (clarithromycin or erythromycin) if penicillin-intolerant

For children <12 years: Co-amoxiclav is first-line; clarithromycin or cefuroxime for penicillin allergy 1

Red Flags Requiring Hospital Evaluation

Urgent hospital referral is indicated for: 1, 5

• Bilateral chest signs on examination 1
• Cyanosis (absolute indication for admission) 5
• Respiratory rate >30/min 1
• Oxygen saturation <92% 5, 6
• Systolic blood pressure <90 mmHg 7, 6
• Altered mental status or drowsiness 1, 5

Common Pitfalls to Avoid

• Do not delay oseltamivir in severely ill patients just because they are beyond 48 hours of symptom onset—hospitalized patients with severe disease benefit regardless of timing 5
• Do not prescribe antibiotics empirically for uncomplicated influenza in previously healthy patients without evidence of bacterial superinfection 1
• Do not withhold antivirals from immunocompromised or elderly patients who lack documented fever but have other influenza symptoms 1
• Do not use aspirin in children with influenza due to Reye's syndrome risk 1

Follow-Up Instructions

• Most uncomplicated cases resolve within 7 days, though cough and fatigue may persist for weeks 6
• Arrange follow-up for high-risk patients, those with complications, or worsening of underlying conditions 6
• Reassess immediately if symptoms worsen (increasing dyspnea, recrudescent fever after initial improvement, severe earache, vomiting >24 hours) 1, 6