Clinical trials are typically conducted in three phases to measure a vaccine's efficacy:
Phase I: Tests the vaccine on a small group of people to evaluate its safety, dosage, and initial efficacy. Phase II: Expands the trial to a larger group to further assess safety and efficacy. Phase III: Involves thousands of participants to confirm efficacy and monitor adverse effects.
These trials are critical in ensuring that a vaccine is both safe and effective before it is approved for public use.
