Español | Other Languages
NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

CSTE Position Statement(s)

  • 11-ID-07

Clinical Criteria

  • Hospital admission date 14 days or less after a positive influenza test, OR
  • Hospital admission date 3 days or less before a positive influenza test

Laboratory Criteria For Diagnosis

Evidence of a positive influenza test by at least one of the following methods:

  • Positive viral culture for influenza
  • Positive immunofluorescence antibody staining (Direct [DFA] or indirect [IFA]) for influenza
  • Reverse transcriptase polymerase chain reaction (RT-PCR) positive for influenza
  • Serologic testing positive for influenza
  • A positive, unspecified influenza test noted in the medical chart (e.g., a written note in the admission H&P or discharge summary)
  • A positive commercially available rapid diagnostic test for influenza

Case Classification


A case that meets the clinical and laboratory evidence criteria.