Influenza Clinical Management
In most cases, laboratory diagnostic testing to determine if a patient has influenza (or which type or subtype) will not be available in time for providers to make clinical decisions. Clinicians should always use clinical judgment when deciding on care. When influenza is circulating in the community, use surveillance data to guide clinical decisions.
The following guidance reflects up-to-date recommendations from the NYC Health Department and the Centers for Disease Control and Prevention.
Treatment
Most cases of influenza are mild, and most patients can be managed in the outpatient setting or over the telephone. Patients who have mild influenza-like illness (a fever of more than 100° F, with cough or sore throat) and are not at a high risk for severe illness and complications usually do not require antiviral medication, though clinicians may prescribe antivirals to these patients to reduce the number of days of influenza symptoms.
Patients should receive early empiric treatment with antiviral medications (ideally within 48 hours of illness onset) if they:
- Have a severe illness, such as an unexplained acute febrile respiratory illness.
- Are hospitalized.
- Have mild influenza-like illness but are in a high risk group.
Even if you cannot initiate treatment for these types of patients with 48 hours of illness onset, patients may still benefit from antiviral medication. All patients who are hospitalized for suspected or confirmed influenza should be treated, regardless of when the illness first presented.
Currently, the Health Department recommends the following drugs to treat influenza:
- Oseltamivir
- Zanamivir
- Peramivir
- Baloxavir
Diagnostic Testing
Diagnostic testing for influenza is generally not necessary for most patients with mild influenza-like illness.
Commercially available rapid test kits have poor sensitivity for detecting influenza. A positive result is indicative of infection, but a negative result should not be used to rule out influenza.
More sensitive assays, including RT-PCR, for subtyping of influenza A are available commercially, but they are not available at the point of care. Results of these tests may not be available within 48 hours of illness onset (i.e., in time for treatment decisions).
The NYC Public Health Laboratory does not accept individual specimens for influenza diagnostic testing, except as part of ongoing surveillance programs.