A fentanyl vaccine developed by University of Houston researchers and sponsored by ARMR Sciences has entered Phase 1/2 human trials, according to JAMA’s coverage. The trial uses healthy volunteers who, once they develop antibodies, take part in a monitored fentanyl challenge to see whether the vaccine protects against the drug’s effects on breathing.

Separately, Axios reported on October 5 that University of Washington researchers are closing in on human testing of their own candidate, which means more than one program may soon be in people.

What it means: This is early-stage safety and proof-of-concept work. It does not show the vaccine prevents real-world overdoses, and larger trials would still be needed.

See the full candidate list and timeline on the Fentanyl Vaccine Status page.

Sources: JAMA, Axios Seattle.