2016-2017 Influenza Antiviral Recommendations

Hello. I am Angela Campbell, a physician in the Influenza Division at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia. It is my pleasure to speak with you as part of the CDC Expert Commentary Series on Medscape.

Today I'll be discussing influenza antiviral medications and reviewing CDC's recommendations for the treatment of influenza. However, I want to begin by emphasizing that vaccination remains the most important influenza prevention tool. CDC recommends ongoing vaccination as long as influenza viruses are circulating, so please continue to vaccinate your patients as you see them over the course of the season. Your recommendation and offer of vaccination are a tremendous motivator to patients.

While influenza is unpredictable, laboratory data suggest that influenza A (H3N2) viruses are predominating during the 2016-17 season. Influenza A (H3N2)–predominant seasons often are associated with more severe illness, especially in young children and older adults. While serious influenza complications can occur in people of any age, certain people are at greater risk for complications, including pregnant women, adults aged 65 or older, children younger than 2 years of age, and people with underlying health conditions like immunosuppression, asthma, diabetes, or heart disease. Influenza vaccination—and treatment—among high-risk patients is critical.

Influenza antiviral medications are an important adjunct to vaccination. While any person can be treated with influenza antivirals, CDC recommends rapid empiric treatment of high-risk persons with influenza symptoms. Clinical judgment, on the basis of the patient's disease severity and progression, age, underlying medical conditions, likelihood of influenza, and time since onset of symptoms, is important when making antiviral treatment decisions for high-risk outpatients.

Antiviral treatment is also recommended as early as possible for any patient with confirmed or suspected influenza who is hospitalized or who has severe, complicated, or progressive illness. A recent study has shown that among hospitalized patients with laboratory-confirmed influenza, antiviral treatment increased from 72% in 2010-11 to 89% in the 2014-15 season.^[1] However, only about half of these patients were treated on the day of hospital admission.

Because clinical benefit is greatest when antiviral drugs are administered early, CDC encourages clinicians not to delay decisions about starting antiviral treatment while waiting for laboratory confirmation of influenza. When indicated, antiviral treatment should be started as soon as possible after illness begins, ideally within 48 hours of symptom onset. However, antiviral treatment may still provide some benefit in hospitalized patients even when begun after 48 hours of illness onset.

Last, antiviral treatment also can be considered on the basis of clinical judgment for previously healthy outpatients with confirmed or suspected influenza who are not in one of the high-risk groups, if treatment can be initiated within 48 hours of illness onset.

CDC's recommendations for using influenza antiviral medications are based on data from randomized clinical trials as well as from observational studies of patients receiving treatment in medical practice. Early antiviral treatment in people with influenza can lessen illness severity, shorten time of illness, and reduce serious flu-related complications such as pneumonia in outpatients and death in hospitalized patients. (See Antiviral Guidance References.)

The three prescription antiviral medications recommended for treatment of influenza are oral oseltamivir, inhaled zanamivir, and intravenous peramivir. These neuraminidase inhibitors are chemically related and have activity against both influenza A and B viruses. Generic oseltamivir was approved by the US Food and Drug Administration (FDA) in August 2016 and became available in December. (See FDA Approves First Generic Tamiflu.)

To treat influenza, oral oseltamivir and inhaled zanamivir are usually prescribed for 5 days, although hospitalized patients may receive treatment for longer. Intravenous peramivir is administered in a single infusion over 15-30 minutes. Peramivir is approved for treatment in adults, zanamivir for treatment of children 7 years or older, and oseltamivir for treatment even in infants. Antiviral dosage information for different age groups is available at CDC's Influenza Antiviral Medications: Summary for Clinicians webpage.

Antiviral resistance among circulating influenza viruses to any of the neuraminidase inhibitor antiviral drugs is currently low, but rare, sporadic cases of antiviral resistance can occur. CDC publishes weekly surveillance data, including information on antiviral resistance, in the FluView US Influenza Surveillance Report.

To close, I will remind you once again that vaccination remains the most important step to prevent influenza, and antiviral medications can be a useful second line of defense to treat influenza illness when indicated. Please see the CDC website for complete guidance on treatment of influenza.

Thank you.

Web Resources

Influenza Antiviral Medications: Summary for Clinicians

2016-17 Information for Health Care Professionals

Antiviral Guidance References

FAQ 2016-17 Influenza Season

FluView US Influenza Surveillance Report