Monitoring for fentanyl within Australian supervised injecting facilities: Findings from feasibility testing of novel methods and collaborative workshops.

The high false positive rates with FTS, relative to the small number of positive results and potential for them to undermine confidence in FTS emphasised the need for confirmatory testing. The role of routine surveillance was unclear within the current low-fentanyl context, however, a process was developed to upscale testing should signals of increased fentanyl prevalence in the Australian heroin market emerge.