Treatment of Influenza A and B with Elevated WBC
Start oseltamivir 75 mg orally twice daily for 5 days immediately for this patient with confirmed influenza A and B, regardless of symptom duration. 1, 2, 3
Immediate Treatment Approach
The elevated WBC count of 13.8 does not change the primary treatment strategy for confirmed influenza. Initiate antiviral therapy with oseltamivir as soon as possible without delay, as early treatment (ideally within 24-48 hours of symptom onset) provides the greatest benefit in reducing illness duration by approximately 24 hours and may decrease hospitalization rates. 1, 2, 4
Oseltamivir Dosing
- Adults and adolescents ≥13 years: 75 mg orally twice daily for 5 days 1, 2, 3
- Children ≥12 months: Weight-based dosing
Alternative Antivirals
- Zanamivir (inhaled): 10 mg (two 5-mg inhalations) twice daily for 5 days for patients ≥7 years if oseltamivir is contraindicated or not tolerated 1, 2, 5
- Peramivir (IV): Consider for severely ill patients with concerns about oral absorption 1, 2
Critical Consideration: Bacterial Coinfection
The positive influenza test does NOT exclude bacterial coinfection, and the elevated WBC of 13.8 warrants careful clinical assessment for concurrent bacterial infection. 1
When to Add Antibiotics
Do NOT routinely add antibiotics unless specific clinical features suggest bacterial coinfection: 6, 7
- Initial severe disease presentation with high fever, productive purulent sputum, or focal lung consolidation 6
- Clinical deterioration after initial improvement (suggesting secondary bacterial pneumonia) 6
- Failure to improve after 3-5 days of antiviral treatment 6
- Radiographic evidence of bacterial pneumonia with lobar consolidation 1
Diagnostic Workup for Suspected Bacterial Coinfection
If bacterial coinfection is suspected based on clinical presentation: 1
- Blood cultures (preferably before antibiotic initiation) 1
- Pneumococcal urine antigen 1
- Sputum Gram stain and culture (if patient can produce purulent sample and has not received prior antibiotics) 1
- Chest X-ray to assess for infiltrates 1
Antibiotic Selection if Bacterial Coinfection Present
For non-severe pneumonia (outpatient or mild hospitalized): 2
- Oral co-amoxiclav or doxycycline 2
For severe pneumonia (CURB-65 score ≥3 or bilateral infiltrates): 2
- IV combination therapy with broad-spectrum β-lactam (e.g., ceftriaxone) PLUS macrolide (e.g., azithromycin) 2
- Administer within 4 hours of admission 2
Monitoring and Follow-Up
Continue Antiviral Therapy
- Standard duration: 5 days 1, 2, 3
- Consider longer duration for immunocompromised patients, those with persistent fever after 6 days, or critically ill patients 2, 6
Reassess Clinical Status
Monitor for: 1
- Temperature, respiratory rate, pulse, blood pressure, oxygen saturation at least twice daily 1
- Signs of clinical deterioration suggesting bacterial superinfection 6
- Development of respiratory distress requiring escalation of care 1
Important Clinical Pitfalls
Taking oseltamivir with food reduces gastrointestinal side effects (nausea and vomiting occur in ~10-15% of patients). 2
Do NOT withhold oseltamivir if >48 hours from symptom onset in hospitalized, severely ill, or high-risk patients, as treatment may still provide mortality benefit. 2, 4, 6
Do NOT use corticosteroids as adjunctive therapy for seasonal influenza treatment. 6
Do NOT use amantadine or rimantadine due to high resistance rates among circulating influenza A viruses. 2, 6
A positive influenza test does NOT mean antibiotics should be automatically withheld—clinical judgment regarding bacterial coinfection remains essential, particularly with an elevated WBC count. 1, 7