Treatment
- Influenza antiviral treatment is recommended for any patient with confirmed or suspected influenza who
- is hospitalized
- has severe, complicated, or progressive illness
- is at high risk for complications or severe disease
- Consider antiviral treatment for any outpatient with confirmed or suspected influenza, regardless of rapid diagnostic testing results, if treatment can be initiated within 48 hours of illness onset
- antiviral therapy should be started as soon as possible
- ideally within 48 hours of symptoms
- may be continued beyond 48 hours to benefit patients with severe, progressive, or complicated disease
- do not delay treatment while awaiting confirmatory test results
- neuraminidase inhibitors are considered first-line therapy based on antiviral resistance patterns
- oseltamivir 75 g orally twice daily for 5 days (consider oseltamivir 150 mg orally twice daily and longer treatment durations for immunocompromised patients)
- zanamivir 10 mg (2 inhalations) twice daily for 5 days
- peramivir 300 mg or 600 mg IV single dose
Infection control
- patients with influenza-like illness should remain isolated (out of school, work, and away from gatherings) until free of fever (100°F [37.8°C]) for ≥24 hours
- patients in high-risk or healthcare settings may be encouraged to isolate for 7 days after symptom onset or until free of fever for ≥24 hours, whichever is longer
- encourage good hand hygiene and respiratory etiquette
Risk factors for complicated or severe disease course
- high-risk conditions for increased risk of influenza complications include
- children <5 years old, especially children <2 years old
- adults ≥65 years old
- pregnant women and women ≤2 weeks postpartum
- persons with chronic medical conditions including
- pulmonary disease including asthma
- cardiovascular disease (except hypertension alone)
- renal disease
- hepatic disease
- hematologic disease including sickle cell disease
- metabolic disorders including diabetes mellitus
- neurologic or neurodevelopment disorders
- persons with immunosuppression due to medications or disease, such as HIV infection
- persons <19 years old on long-term aspirin therapy (who might be at risk for Reye syndrome after influenza virus infection)
- American Indians/Alaskan Natives
- patients in chronic care facilities
- persons with morbid obesity (BMI ≥40 kg/m2)
Complications
- common complications include
- pneumonia
- otitis media
- tracheobronchitis
- acute sinusitis
- exacerbations of chronic pulmonary or cardiac disease
- less common complications include
- Reye syndrome in children and adolescents taking aspirin
- myocarditis
- pericarditis
- myositis
- myoglobinuria
- neurological sequelae
- Guillain-Barré syndrome
- transverse myelitis
- encephalitis
Prognosis
- uncomplicated influenza illness typically resolves after 3-7 days, but cough and malaise can persist >2 weeks
Prevention
- annual immunization for all individuals aged >6 months remains the most effective method of reducing influenza infection and related complications
- Post-exposure chemoprophylaxis
- consider early treatment as alternative to chemoprophylaxis
- consider postexposure prophylaxis with oseltamivir or zanamivir for higher-risk persons exposed to patients with influenza; this may be limited to patients in healthcare settings such as transplant units, neonatal units, or other patients with severe immunosuppression or other highly vulnerable patients
- drug of choice for antiviral chemoprophylaxis is either oseltamivir or zanamivir, but monitor local antiviral resistance surveillance data.
Alan Drabkin, MD, is a senior clinical writer for DynaMed, a database of comprehensive updated summaries covering more than 3,200 clinical topics, and assistant clinical professor of population medicine at Harvard Medical School.
