Clinical trials are conducted in several phases to ensure the safety and efficacy of a vaccine:
1. Phase I: Tests the vaccine on a small group of healthy volunteers to assess safety and immune response. 2. Phase II: Involves a larger group to further evaluate safety, dosing, and immunogenicity. 3. Phase III: Expands the study to thousands of participants to confirm efficacy and monitor for adverse effects. 4. Phase IV: Post-licensure studies that continue to monitor vaccine safety and effectiveness in the general population.
