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CDC: Influenza B Linked to Half of Flu-Related Hospitalizations This Season

January 13, 2020

According to the Centers for Disease Control and Prevention (CDC), roughly half of the flu-related hospitalizations during the 2019-2020 influenza season so far have been associated with influenza B infections.

Specifically, influenza B/Victoria viruses have been the most frequently reported circulating strains, followed by A(H1N1)pdm09, which comprise the majority of the remaining half of influenza-related hospitalizations. Despite this, influenza A virus activity is increasing and becoming predominant some regions.

“In past seasons, the proportion of influenza-related pediatric deaths associated with influenza B viruses has generally been higher than the proportion of influenza B among circulating viruses, and pediatric mortality from influenza B–associated hospitalizations has been reported to be higher than with influenza A–associated hospitalizations,” CDC wrote.

“So far this season, influenza B virus infections account for about half of hospitalizations reported through CDC’s laboratory-confirmed influenza hospitalization surveillance network and the majority of reported influenza-associated pediatric deaths.”

CDC recommendations for clinicians are as follows:

  • All individuals aged 6 months and older not yet vaccinated this season should be vaccinated against influenza. No formulation is recommended over another.
  • Treat all hospitalized, severely ill, and high-risk patients, regardless of vaccination status, with antivirals as soon as possible following onset of influenza symptoms.
  • Antiviral treatment may be given to non-high-risk patients with suspected or confirmed influenza who presents within 2 days after illness onset.
  • Four influenza antiviral medications are approved for use in the US. Recommendations for choosing which option is best for each patient are available from the CDC.
  • Antiviral treatment should be started as soon as possible and not wait for laboratory confirmation of influenza.  

“The Centers for Disease Control and Prevention reminds clinicians that influenza B viruses can cause severe illness in people of all ages, including children. CDC continues to recommend influenza vaccination and prompt antiviral treatment of high-risk outpatients and hospitalized patients with suspected influenza.”

—Michael Potts


Elevated Influenza Activity: Influenza B/Victoria and A(H1N1)pdm09 viruses are the predominant viruses [press release]. CDC Health Alert Network. January 10, 2020. Accessed January 13, 2020.

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