Vaccine development process is long (average of 12-15 years), complex and costly. In addition to costs, other key challenges include identifying suitable antigens, adjuvants, and acceptable delivery methods, regulatory approvals, technical and manufacturing hurdles. In brief, the stages of a vaccine development are:
a) Pre-clinical stage: Done in the laboratory and in animals with broad aim being to assess antigen safety and select the best candidate vaccine. Among common activities at this stage are:
- Exploratory selection of the right proteins (antigens) to use in preventing or treating the disease
-Creation of the vaccine concept
-Evaluation of vaccine efficacy in test tubes and animals
-Manufacture of the vaccine to Good Manufacturing Practice standards
b) Clinical development stage: Done in a carefully controlled environment with human volunteers. The vaccine is first tested in small number of volunteers and involves 4 phases:
-Phase I clinical trials are small-scale trials to assess whether the vaccine is safe in humans and what immune response it evokes.
-Phase II clinical trials are larger and look mainly to assess the efficacy of the vaccine against artificial infection and clinical disease. Vaccine safety, side-effects and the immune response are also studied.
-Phase III clinical trials are studied on a large scale of many hundreds of subjects across several sites to evaluate efficacy under natural disease conditions. If the vaccine retains safety and efficacy over a defined period, the manufacturer is able to apply to the regulatory authorities for a licence to market the product for human use. For regulatory approval, all the data collected through the preceding stages are submitted to the relevant health authorities for approval
-Phase IV happens after the vaccine has been licensed and introduced into use. Also called post-marketing surveillance, this stage aims to detect rare adverse effects that could not be detected in previous stages as well as to assess the long term efficacy.
The Vaccine Safety Net is a global network of websites, evaluated by the World Health Organization, that provide reliable information on vaccine safety.
Vaccines for Africa Initiative (VACFA)
Institute of Infectious Diseases and Molecular Medicine (IDM)
Wernher & Beit North Wing, Room N2.09A
University of Cape Town
Faculty of Health Sciences
Observatory, 7925, Cape Town, South Africa