What are the management options for a patient with influenza, considering severity of symptoms, underlying medical conditions, and risk for complications?

Management of Influenza

Immediate Treatment Decision: Antivirals

For patients presenting within 48 hours of symptom onset with fever >38°C and acute influenza-like illness, oseltamivir 75 mg orally twice daily for 5 days should be initiated immediately, as this reduces illness duration by approximately 24 hours and may prevent serious complications. 1, 2, 3

Antiviral Therapy Criteria

• All three criteria must be met for routine outpatient antiviral treatment: 1, 3

  • Acute influenza-like illness
  • Fever >38°C (>38.5°C in children)
  • Symptomatic for ≤48 hours

• Treatment is most effective when started within 24 hours of symptom onset, though benefit extends to 48 hours 2, 4, 5

• Hospitalized or severely ill patients should receive oseltamivir even if >48 hours from symptom onset, particularly if immunocompromised 1, 3

• Zanamivir (inhaled) is an alternative for patients unable to take oseltamivir, but is not recommended for patients with underlying airways disease due to risk of fatal bronchospasm 3, 6

Dosing Adjustments

• Reduce oseltamivir dose by 50% (75 mg once daily) if creatinine clearance <30 mL/minute 1
• Elderly and immunocompromised patients may not mount adequate febrile response but remain eligible for treatment 1, 7

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Symptomatic Management

All patients should receive supportive care regardless of antiviral eligibility. 1, 3

First-Line Symptomatic Treatment

• Paracetamol or ibuprofen for fever, myalgias, and headache 1
• Adequate hydration and rest 1, 3
• Avoid smoking 1
• Short course of topical decongestants (maximum 3 days to avoid rebound congestion), throat lozenges, saline nose drops 1, 2

Critical Caveat for Children

• Aspirin is absolutely contraindicated in children <16 years due to Reye's syndrome risk 3

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Antibiotic Management: When and What to Prescribe

Antibiotics are NOT routinely indicated for uncomplicated influenza in previously healthy adults. 1, 3

Indications for Antibiotics in Adults

Consider antibiotics if any of the following are present: 1

1. Worsening symptoms after initial improvement (recrudescent fever, increasing dyspnea) suggesting bacterial superinfection
2. Severe pre-existing illnesses (COPD, heart disease, diabetes)
3. Features of pneumonia: focal chest signs, respiratory rate >30/min, bilateral chest signs, or CRB-65 score ≥3

Antibiotic Regimens for Adults

For influenza-related pneumonia managed in the community: 1

• First-line: Doxycycline 200 mg loading dose, then 100 mg once daily OR co-amoxiclav 625 mg three times daily for 7 days
• Alternative (penicillin allergy): Clarithromycin 500 mg twice daily OR erythromycin 500 mg four times daily
• These regimens cover S. pneumoniae, H. influenzae, M. catarrhalis, and critically, S. aureus (a major cause of secondary bacterial pneumonia with high mortality) 1, 8

For severe pneumonia requiring hospitalization: 1, 3

• IV co-amoxiclav OR 2nd/3rd generation cephalosporin (cefuroxime, cefotaxime) PLUS macrolide (clarithromycin or erythromycin)
• Antibiotics must be administered within 4 hours of admission 3

Antibiotic Regimens for Children

Children requiring antibiotics (see indications below): 1

• Age <12 years: Co-amoxiclav (first-line)
• Penicillin allergy: Clarithromycin OR cefuroxime
• Age >12 years: Doxycycline is an alternative

Indications for antibiotics in children: 1

1. High-risk for complications (chronic lung disease, heart disease, immunosuppression)
2. Breathing difficulties
3. Severe earache (otitis media is common)
4. Vomiting >24 hours
5. Drowsiness
6. Disease severe enough to merit hospital admission

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Severity Assessment and Hospital Referral

CURB-65 Score for Pneumonia Severity

Use CURB-65 to stratify patients with influenza-related pneumonia: 1

• Confusion
• Urea >7 mmol/L
• Respiratory rate ≥30/min
• Blood pressure: systolic <90 mmHg or diastolic ≤60 mmHg
• Age ≥65 years

Hospital Referral Criteria

Urgent hospital referral is required for: 1, 7

• CURB-65 score ≥3 (high risk of death)
• Bilateral lung infiltrates on chest X-ray (manage as severe pneumonia regardless of CURB-65 score)
• CRB-65 score ≥3 (community version without urea)
• Oxygen saturation <90% 1, 7
• Respiratory rate >30/min 2, 7

Consider hospital admission for CURB-65 score of 2 (increased risk of death; clinical judgment required) 1

Low-risk patients (CURB-65 score 0-1) can be treated at home 1

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Red Flag Symptoms Requiring Immediate Re-evaluation

Patients should seek urgent care if they develop: 2, 3, 7

• Respiratory distress: increasing shortness of breath, respiratory rate >30/min, difficulty breathing
• Persistent high fever: temperature >37.8°C lasting >4 days
• Hemodynamic instability: heart rate >100/min, systolic blood pressure <90 mmHg
• Hypoxia: oxygen saturation <90% or cyanosis
• Neurological changes: altered mental status, confusion, drowsiness, seizures
• Severe dehydration: inability to maintain oral intake, vomiting >24 hours
• Worsening after initial improvement: recrudescent fever or increasing dyspnea (suggests bacterial superinfection)

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Special Populations

Children

• Children <1 year and those at high risk should be assessed by a physician 1, 3
• Children aged 1-7 years may be seen by a nurse or GP; those ≥7 years may be seen by community health team 1

Pregnant Women

• Pregnant women are at high risk of complications and should be treated with antivirals 9

Elderly and Immunocompromised

• May not mount adequate febrile response but remain eligible for antiviral treatment 1, 7

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Expected Clinical Course and Follow-Up

Typical Recovery Timeline

• Illness typically resolves within 7 days, but cough, malaise, and fatigue commonly persist for several weeks 2, 7
• This prolonged recovery is normal and does not necessarily indicate complications 2

Follow-Up Indications

Follow-up is NOT routinely required for uncomplicated cases in previously healthy adults 2, 7

Follow-up should be arranged for: 7

• Patients who suffered significant complications
• Significant worsening of underlying disease
• High-risk patients (elderly, immunocompromised, chronic disease)

Patients should be reviewed 24 hours prior to hospital discharge and should remain hospitalized if they have ≥2 unstable clinical factors (temperature >37.8°C, heart rate >100/min, respiratory rate >24/min, systolic blood pressure <90 mmHg, oxygen saturation <90%, inability to maintain oral intake, abnormal mental status) 1, 7

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Infection Control Measures

To prevent transmission: 2

• Strict hand hygiene: handwashing or alcohol-based hand gels, especially after coughing/sneezing
• Respiratory etiquette: cover nose and mouth with tissue when coughing/sneezing, dispose immediately, or cough/sneeze into sleeve (not hands)
• Avoid contact with others, especially high-risk individuals, until fever-free for 24 hours without antipyretics
• Remain off work while symptomatic

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Prevention: Annual Vaccination

Annual influenza vaccination is recommended for all people ≥6 months of age who do not have contraindications, and is the most effective prevention strategy 2, 4, 5

• Vaccination should occur at the beginning of flu season (typically October) 4
• Peak antibody protection occurs approximately 14 days after vaccination 4