Norovirus result-reporting update

Please be aware that resulting of the NOROVIRUS target in Epic for all molecular GI panels in the PEAKS region has changed from DETECTED to INDETERMINATE when positive.

This change was made due to cross-reactivity of the Norovirus target with certain GI bacteria leading to increased false positive Norovirus results on the BioFire FilmArray® GI panel(1). Published false positive rates range from 27.4% to 66.2% (2-4). Providers should interpret these results in the context of clinical findings and consider ordering a confirmatory Norovirus PCR test if warranted by the patient’s symptoms.

During the past several days, a Beaker configuration update was implemented affecting Gastrointestinal Panel results for all sites except for St. Mary’s Regional Hospital Laboratory. The result will append with the following interpretive comment:

“Cross-reactivity with other organisms may give false-positive Norovirus results, especially when prevalence in the community is low.”

An additional sentence is planned to be added to this interpretive comment to remind providers that “If clinically indicated, confirmatory testing is available by request.” This enhancement is pending an analyst build update and is not live in Epic at this time.

This shift aligns with standardized reporting practices used in other regions at Epic go-live and is meant to reduce the risk of misdiagnosing a patient due to a false positive result.

Key points to note

• This update applies to all sites except St. Mary’s Regional Hospital Laboratory.

• The change standardizes reporting with current practices in the Canyons and Desert regions.

• It applies to all Gastrointestinal Molecular Panel testing performed on the bioMérieux BioFire Torch platform.

Please contact the laboratory with any questions regarding this update. Thank you.

REFERENCES:

1. Link to BioFire FDA recall: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfres/res.cfm?id=205002

2. Michael Daley and others. Continued norovirus false positivity after FDA clearance of the BioFire FilmArray gastrointestinal panel. J Clin Micro. 30 March 2026

3. Melissa Caza, and others. Investigation of suspected false positive norovirus results on a syndromic gastrointestinal multiplex molecular panel. J of Clin Virology. Vol 175. Dec 2024.

4. Nancy Matic, and others. Melting curve analysis reveals false-positive norovirus detection in a molecular syndromic panel. J of Clin Virology. Vol 173. Aug 2024.