Phase Goal
Pre-clinical trialsStudies of the vaccine candidate in the laboratory or in
non-human animals
Phase I clinical trialStudies of fewer than 100 people to assess safety of vaccine candidate
Phase II clinical trialStudies of several hundred people to preliminarily test safety and immune response
Phase III clinical trialStudies of thousands of people to formally test safety and efficacy
Phase IV clinical trial/
post-marketing surveillance		Ongoing studies of the vaccine after it has been approved