Accelerating Subtyping of Influenza A in Hospitalized Patients

Actions requested

• About

  Be aware that due to the ongoing avian influenza A (H5) virus outbreak in the United States, CDC is recommending accelerating subtyping of all influenza A virus-positive specimens from hospitalized patients to identify severe human infections with avian influenza A (H5) viruses.

• Identify

  Continue to assess patient’s potential exposure history to avian influenza A (H5) presenting for care with signs or symptoms of acute respiratory illness, influenza-like-illness or conjunctivitis, or who are positive for influenza A:

  • Exposure to sick or dead wild birds or domestic animals such as agricultural and farm workers, and backyard flocks,
  • Exposure to raw animal products such as raw cow milk and raw pet food,
  • Close contact with a symptomatic person diagnosed with avian influenza A (H5)
• Test

  • Perform influenza A testing for all hospitalized patients with suspected influenza
  • Subtype all influenza A positive specimens in hospitalized patients, especially patients in the Intensive Care Unit (ICU) or patients with an exposure history to influenza A (H5): 
    • If a patient tests positive for influenza via a rapid diagnostic test, providers are encouraged to collect a new specimen that allows for influenza subtyping
  • If possible, subtyping tests should be performed in the hospital clinical laboratory or sent to a commercial laboratory
  • For hospitals that do not perform subtyping and do not send to commercial lab for subtyping:
  • If patient has exposure history OR there is clinical suspicion for avian influenza A (H5), notify Public Health – Seattle & King County (PHSKC) immediately. Specimens can be sent directly to Washington State Public Health Laboratory (WAPHL) for influenza A (H5) testing.
  • If patient has no exposure history AND there is no clinical suspicion for avian influenza A (H5), specimens can be sent directly to WAPHL as routine. Notifying PHSKC is not needed. This is a change to the previous protocol
  • WAPHL will prioritize specimens in the following manner: 
    1. Influenza A-positive specimens from hospitalized patients with known exposure to sick or deceased animals, raw animal products, or suspected or confirmed avian influenza A (H5) patients
    2. Influenza A specimens with an unsubtypeable result
    3. Influenza A specimens that have NOT yet been subtyped from a patient admitted to an ICU
    4. All other hospitalized patients testing positive for influenza A whose specimens have NOT yet been subtyped
  • If subtyping is performed at hospitals, and the specimen is unsubtypeable (not H1 or H3):
  • Submit any unsubtypeable specimens to WAPHL for additional typing according to WA DOH testing guidance for influenza within 24 hours of identification;
  • AND notify PHSKC
  • See WA DOH Subtyping of Influenza A Recommended for Hospitalized Patients for more detailed information on subtyping at WAPHL
• Notify

  Immediately report the following to Public Health at 206-296-4774:

  • Any suspected human case of novel or avian influenza and/or
  • Influenza A-positive specimens that are reported as unsubtypeable (not identified as H1 or H3)
• Manage

  • Initiate empiric influenza antiviral therapy as soon as possible in patients with suspected avian influenza A (H5) infection, especially those in an ICU
    • Antiviral treatment should not be delayed while waiting for laboratory results.
  • Standard, contact and airborne precautions, including the use of eye protection, are recommended when evaluating patients for infection with novel influenza A viruses.