Table 1.
Major characteristics of vaccine development processes.
| Stage |
Appraisal |
Approximate duration |
Comment |
|---|---|---|---|
| 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 | ||
| 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 • Involving 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 | • Conducting after vaccine releasing • Testing safety, efficacy, & other potentials by manufacturer • Collecting data from vaccinated individuals |