Phase 3 trial

The last and largest stage of testing a new drug or vaccine in people, usually with hundreds or thousands of patients. Good Phase 3 results are normally needed before regulators approve it.

Also called: Phase 3, Phase III, Phase III trial, late-stage trial.

Related terms

  • Hazard ratio: A number from medical trials that compares how often something bad happens, like a cancer coming back, in patients who got a treatment versus those who didn't. A hazard ratio of 0.58 means about 42% lower risk.

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