What happens in each phase of clinical trials?Phase	GoalPre-clinical trials	Studies of the vaccine candidate in the laboratory or innon-human animalsPhase I clinical trial	Studies of fewer than 100 people to assess safety of vaccine candidatePhase II clinical trial	Studies of several hundred people to preliminarily test safety and immune responsePhase III clinical trial	Studies of thousands of people to formally test safety and efficacyPhase IV clinical trial/post-marketing surveillance	Ongoing studies of the vaccine after it has been approved