Fiona Havers, MD
December 19, 2017
Now that flu season is here, it’s a good time to remember that although prevention through vaccination is the best line of defense against flu, treatment options are available and should be administered promptly, especially to high-risk patients.
High-risk patients (pregnant women; adults aged 65 years or older; children younger than 2 years; and people with underlying health conditions, such as immunosuppression, asthma, diabetes, or heart disease) are at greater risk of developing flu complications. When administered early, antiviral treatment of people with influenza can lessen illness severity; shorten the duration of illness; and reduce serious flu-related complications, such as pneumonia in outpatients and death in hospitalized patients.
Prescribing Antiviral Medications
However, when it comes to prescribing antiviral medications for high-risk patients, there is definitely room for improvement. A recent study showed that although high-risk patients with respiratory illness who sought care early were more likely to receive antiviral prescriptions, only 37% of high-risk patients with confirmed influenza were actually prescribed antiviral medications. The study also found that many high-risk patients delayed seeking care, thereby reducing the opportunity for optimal antiviral treatment.
These findings emphasize the importance of developing a deeper understanding of the barriers to prescribing antivirals and the need to create new methods to increase appropriate prescribing for high-risk patients. Furthermore, this study highlights the need to further educate healthcare providers about the benefits of antiviral medications.
Influenza Antiviral Recommendations
The Centers for Disease Control and Prevention’s (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. CDC recommends antiviral treatment as early as possible for any patient with confirmed or suspected influenza who is hospitalized; has severe, complicated, or progressive illness; or is at higher risk for influenza complications because of age or underlying medical conditions. Clinical judgment, based on 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.
Three prescription antiviral medications are recommended for the treatment of influenza: 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, which was approved by the US Food and Drug Administration in August 2016, became available in December 2016.
Clinical benefit is greatest when antiviral drugs are administered early. Given this, 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 for all high-risk, hospitalized, or severely ill patients. However, antiviral treatment might still provide some benefit in hospitalized patients even when begun after 48 hours of illness onset.
Clinicians also can consider antiviral treatment on the basis of clinical judgment for previously healthy outpatients with confirmed or suspected influenza, even if they are not considered high risk, if treatment can be initiated within 48 hours of illness onset.
To treat influenza, oral oseltamivir and inhaled zanamivir are usually prescribed for 5 days, although hospitalized patients may receive longer treatment. Intravenous peramivir is administered in a single infusion over 15-30 minutes. Peramivir is approved for treatment in adults; zanamivir for the treatment of children aged 7 years or older; and oseltamivir for treatment in patients of all ages, including infants. Antiviral dosage information for different age groups is available at CDC’s Influenza Antiviral Medications: Summary for Clinicians.
Flu Season and Antiviral Resistance
Although influenza is unpredictable, laboratory data suggest that influenza A (H3N2) viruses are thus far predominating during the 2017-2018 season. Influenza A (H3N2)-predominant seasons often are associated with more severe illness, especially in young children and older adults.
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.
Visit CDC’s Influenza page for the latest updates on flu activity and CDC’s information for healthcare professionals. In addition, for detailed guidance on nonpharmaceutical interventions (NPIs) and how to plan and prepare for a flu pandemic, see the 2017 Community Mitigation Guidelines, NPI Planning Guides, and Pandemic Flu Checklist.