Stage Appraisal Approximate duration Comment
Laboratory & animal studies Laboratory & animal studies Laboratory & animal studies
Exploratory stage
Antigen identification & concept validation
2-4 years
• Research-intensive stage • Desired natural or synthetic antigen detection or production
Preclinical Stage
Safety & immunogenicity of vaccine candidates, starting dose determination for further studies
1-2 years
• Tissue- or cell-culture & animal testing • Adjuvant selection • Immunogenicity studies • Good Laboratory Practices (GLP) safety studies (in vivo validation) • Potency assay development • Infection challenge studies with the animals
Clinical Stages FDA approval during 30 days & subjecting to human studies FDA approval during 30 days & subjecting to human studies FDA approval during 30 days & subjecting to human studies
Phase I
Safety & immunogenicity of vaccine candidates
˂ 1 year
• Involves a small group of healthy adults (20-100 subjects) • Usually, non-blinded studies • May be using challenge model in a small part of participants • An attenuated or modified copy of pathogen applied for challenging • Evaluating local & systemic reactions • Relating dose size to the side effects
Phase II
Safety & immunogenicity, proposed doses, schedule of immunizations method of delivery, partial efficacy
2 years
• Randomized & well-controlled trials • Hundreds of healthy adults • May contain at risk groups • Evaluating clinical & laboratory responses (antibody response) • Determining most common short-term side effects
Phase III
Safety & efficacy
Many years
• Determining efficacy & safety in target population (thousands) • Determining certain rare side effects • Randomized & double-blind studies • Involve the experimental vaccine against placebo • Evaluating disease & infection prevention • Evaluating antibody or other pathogen related immunity
Regulatory approval & licensure
Marketing authorization
In progress
• Submitting a Biologics License Application to the FDA • Inspecting facilities &reviewing the manufacturer’s tests for potency, safety & purity by FDA • Vaccine approval (granted for an initial 5 years)
Phase IV
Post marketing safety & efficacy
In progress
• Conduct after vaccine releasing • Testing safety, efficacy, & other potentials by manufacturer • Collecting data from vaccinated individuals