Clinical trials for experimental vaccines are divided into several phases:
Phase I: Tests the vaccine on a small group of people (20-100) to assess its safety and determine appropriate dosage. Phase II: Involves a larger group (several hundred) to evaluate the vaccine's efficacy and further assess its safety. Phase III: Conducted on thousands of participants to confirm its efficacy, monitor side effects, and compare it to commonly used treatments. Phase IV: Post-marketing studies to gather additional information about the vaccine's risks, benefits, and optimal use.
