Table 2.
Various stages in vaccine development as of January 2021 (Centers of Disease Control & Prevention, 2014; WHO, 2020e).
| Stages | Sub-stages | Description | Number of vaccines |
|---|---|---|---|
| Exploratory Stage | - | Laboratory research to find potential antigens that can help in preventing or treating the disease | Many vaccines across the globe |
| Pre-clinical stage | - | Involves cell-culture systems and animal testing to assess the developed vaccine in terms of safety and immunogenicity. Mice and monkeys are the potential animals subjected to testing | 177 |
| Clinical development | Phase I | The vaccine is tested on a small group of people | Phase 1: 19 Phase 1/2: 19 |
| Phase II | The clinical study is expanded and hundreds of people are tested and some may belong to the groups at risk of acquiring the disease | Phase 2: 5 Phase 2/3: 6 |
|
| Phase III | The vaccine is given to thousands of people and tested for efficacy and safety | 16 | |
| Phase IV | The manufacturer may continue to test the vaccine for safety, efficacy, and other potential uses | - |