Guidance to Commercial Laboratories on Increasing Submission of Influenza A and B Positive Samples to State and Local Public Health Laboratories for Additional Subtyping (including H5)

Testing Guidance

In an effort to enhance surveillance of influenza infections during this outbreak, CDC in coordination with STLT public health agencies, requests that commercial laboratories prospectively increase submissions to their jurisdictional PHL during the spring and summer months when influenza transmission is normally low. This guidance has been developed to ensure the efficient transfer of clinical specimens for additional subtyping testing. Commercial laboratories are encouraged to communicate with the PHL of the patient’s state of residence prior to submitting specimens to obtain the appropriate specimen submission form and any additional submission instructions. Specimens will be tested for surveillance purposes and patient specific reports may not be returned to the submitter.

CDC requests commercial laboratories continue to send the following specimens to PHLs as soon as possible for further testing and characterization.

1. Influenza A positive specimens that are subtype negative on tests designed to provide an influenza subtyping result (ex. Biofire) and confirmed upon retest.
2. Influenza A positive specimens that are subtype influenza A(H1) and not influenza A(H1)pdm09 on tests designed to provide an influenza subtyping result and confirmed upon retest.

For Awareness

Performance characteristics for the CDC in vitro diagnostic reverse transcription real-time polymerase chain reaction (rRT-PCR) subtyping assays have been determined with the following human upper respiratory specimens from patients with signs and symptoms of respiratory infection and/or from viral culture:

1. nasopharyngeal swabs [NPS]
2. nasal swabs [NS]
3. throat swabs [TS]
4. nasal aspirates [NA]
5. nasal washes [NW]
6. dual nasopharyngeal/throat swabs [NPS/TS]

Performance characteristics for the CDC in vitro diagnostic reverse transcription real-time polymerase chain reaction (rRT-PCR) subtyping assays have been determined with the following human lower respiratory tract specimens from patients with signs and symptoms of respiratory infection:

1. bronchoalveolar lavage [BAL]
2. bronchial wash [BW]
3. tracheal aspirate [TA]
4. sputum and lung tissue

Enhanced Surveillance

Submissions of additional influenza A and B positive specimens that have not undergone influenza subtyping testing are greatly appreciated to ensure rapid detection of any human infections of A(H5N1). While submission of as many samples as possible is preferred for the summer months ahead, CDC (in collaboration with APHL) can help to determine an appropriate and feasible number of samples each month in order to prioritize available laboratory resources. Please consider submission of samples that meet the established assay cutoff of your testing method to identify positive samples. CDC will continue to work with commercial laboratories and APHL to determine a process by which samples will be submitted to state and local public health laboratories or national reference laboratories for additional subtype testing.