Fast Five Quiz: Influenza

Michael Stuart Bronze, MD


November 06, 2018

Recently, the FDA approved baloxavir marboxil tablets for the treatment of acute uncomplicated influenza in people aged 12 years and older who have been symptomatic for no longer than 48 hours. This drug is the first new antiviral flu treatment with a novel mechanism of action to be approved by the FDA in approximately 20 years.

The CDC has made the following recommendations regarding the use of antiviral drugs in influenza:

  • Antiviral treatment is recommended as soon as possible for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness or who require hospitalization

  • Antiviral treatment is recommended as soon as possible for outpatients with confirmed or suspected influenza who are at higher risk for influenza complications on the basis of their age or underlying medical conditions; clinical judgment should be an important component of outpatient treatment decisions

  • Currently recommended antiviral medications include oseltamivir and zanamivir

  • Oseltamivir may be used for treatment or chemoprophylaxis of influenza in infants younger than 1 year, when indicated

  • Antiviral treatment also may be considered on the basis of clinical judgment for any outpatient with confirmed or suspected influenza who does not have known risk factors for severe illness, if treatment can be initiated within 48 hours of illness onset

  • Because antiviral resistance patterns can change over time, clinicians should monitor local antiviral resistance surveillance data

The neuraminidase inhibitors (oseltamivir, peramivir, and zanamivir) have activity against influenza A and B viruses (including H1N1), whereas the adamantanes (amantadine and rimantadine) have activity against influenza A viruses only. Since 2006, only the neuraminidase inhibitors have been recommended because of widespread resistance to the adamantanes among influenza A (H3N2) virus strains. Oseltamivir resistance emerged in the United States during the 2008-2009 influenza season.

To be effective as treatment, these agents must be administered within 48 hours of symptom onset. These agents are most effective if started within the first 24 hours of symptoms and less effective if begun 24 to 48 hours after symptoms appear.

Prompt use of antiviral drugs during the 2009 H1N1 influenza pandemic improved survival among severely ill pregnant women. A CDC study of 347 pregnant women (including 272 who required ICU admission but survived and 75 who died) and 15 severely ill postpartum women (9 of whom died) found that 94.8% of survivors received antiviral treatment with oseltamivir or zanamivir compared with 86.1% of those who died, a statistically significant difference. Baloxavir marboxil, an oral cap-dependent endonuclease inhibitor that blocks influenza virus proliferation by inhibiting the initiation of mRNA synthesis, has received approval in Japan for the treatment of influenza and is under study in the United States.

For more about antiviral pharmacologic therapy for influenza, read here.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.