Another carfentanil fatal outbreak in Florida?

Background: In 2016 and 2017, carfentanil was implicated in the deadliest fatal outbreak involving a fentanyl analog in the United States with 1190 deaths in Florida alone. Recent surveillance signals suggest that Florida is experiencing a resurgence in carfentanil-involved deaths. The purpose of this paper is to examine carfentanil-involved overdoses using up-to-date medical examiners reports triangulated with carfentanil-related indicators at multiple levels. Methods: Florida's medical examiner data were analyzed in three periods (2016, 2017, 2018–2023) to examine changes in decedent demographic, geographic, and toxicologic characteristics. We triangulated six additional state and national data sources which included completed death certificates, the National Forensic Laboratory Information System, Reddit mentions, and clinical urine drug tests positive for carfentanil. Results: There were 24 carfentanil-involved deaths in a 2-month period (Dec/Nov 2023). Compared to 2017, recent decedents were significantly older (42.9 years old vs. 37.1 years old, p < 0.0001) with increased exposure to fentanyl (23.4–68.8 %, p < .0001) and methamphetamine (8.5–20.4 %, p = 0.0003). The state's prior three-county epicenter showed limited involvement (6.5 % vs. 18.9 % total carfentanil deaths) when compared to the prior outbreak. All triangulated national data sources showed strong retrospective concordance. More timely death certificate data suggests that monthly carfentanil deaths were more frequent (mean=4 deaths/mo.) in 2024. Conclusions: The state may have averted a fatal outbreak as of December 2024, but carfentanil deaths have reached new monthly levels with increasingly active signals in other systems. These systems should be monitored regularly to decrease lag time in fatal overdose surveillance for a faster public health response.