Influenza A Management Guidelines

Diagnosis and Treatment

The Infectious Diseases Society of America recommends that neuraminidase inhibitors (oseltamivir or zanamivir) should be started as soon as possible within 48 hours of symptom onset in patients with confirmed or suspected influenza A, particularly for those at high risk of complications 1, 2
Laboratory testing is recommended for hospitalized patients and those where confirmation would change management decisions, with preferred diagnostic tests including rapid molecular assays (nucleic acid amplification tests) over rapid influenza diagnostic tests (RIDTs) for improved detection 1
The Centers for Disease Control and Prevention recommends that nasopharyngeal specimens (optimal) or mid-turbinate nasal swabs be collected for better detection, rather than throat swabs 1
For hospitalized patients with respiratory failure on mechanical ventilation, endotracheal aspirate or bronchoalveolar lavage fluid specimens should be collected 1

The American Thoracic Society recommends that antiviral treatment be initiated as soon as possible for hospitalized patients with influenza, regardless of illness duration, as well as for outpatients with severe or progressive illness, high-risk patients, children younger than 2 years, adults ≥65 years, and pregnant women 1, 2, 3
Oseltamivir (Tamiflu) is the preferred first-line treatment, with dosing recommendations including 75 mg twice daily for 5 days for adults and children >24kg, 45 mg twice daily for 5 days for children 15-23 kg, and 30 mg twice daily for 5 days for children ≤15 kg 2, 4
The strength of evidence for oseltamivir treatment is moderate to high, with a reduction in illness duration by approximately 24 hours, possible reduction in hospitalization rates, and reduction in subsequent antibiotic use 2

The British Thoracic Society recommends that patients with pneumonia be assessed using the CRB-65 score to guide management, with scores 0-4 indicating varying levels of severity and need for hospital referral 5, 6
For non-severe influenza-related pneumonia, oral therapy with co-amoxiclav or a tetracycline (e.g., doxycycline) is preferred, while parenteral options include IV co-amoxiclav or a second/third generation cephalosporin 7

The Centers for Disease Control and Prevention recommends that hospitalized patients with influenza be monitored closely, with use of RT-PCR or other molecular assays for improved detection, and consideration of multiplex RT-PCR assays targeting a panel of respiratory pathogens in immunocompromised patients 1
During facility outbreaks, rapid influenza virus testing should be performed on nasopharyngeal specimens from patients with recent symptom onset, and antiviral prophylaxis should be considered for all patients without influenza in the involved unit 3

The American Journal of Respiratory and Critical Care Medicine recommends that annual influenza vaccination remain the primary preventive measure, with consideration of antiviral prophylaxis with oseltamivir (75 mg once daily) for unvaccinated high-risk individuals during local influenza activity 6