Developing a vaccine is a very tedious and lengthy process. With the virus spread all over the world, the requirement for a vaccine becomes even more essential. But the development of a vaccine requires lots of research, lots of funding, and a large number of trials before it finally gets approved.
Often it takes 10-12 yrs for a vaccine to be developed. But with the increasing breakthroughs in technology and advancements in the field of science, has fast-tracked this process. There are various stages to the development of a vaccine that is employed before we finally get one.
- Exploratory Stage: This is the beginning of the vaccine development cycle and usually involves laboratory research. Scientists identify natural or synthetic antigens (weakened toxins etc.) which provide resistance to the disease.
- Pre-clinical Stage: In this stage, the dose is given to animals and assess whether the drug is able to provoke an immune response. Animals used in the trials are monkeys and mice. This study gives the scientists an idea of what kind of response to expect in humans.
- Phase-1 trials: In this phase of trials the vaccine is given to humans. The group of subjects are small and vary in the range of 20-80 individuals. The group usually is made up of adults. The scientists assess the safety of the drug on humans and also observe the immune response.
- Phase-2 trials: In this phase, the size of the group to be tested is increased to several hundred. This group includes individuals who are at higher risk of contracting the disease. Scientists observe the safety parameters, immunogenicity, and methods of delivery.
- Phase-3 trials: The group size is increased is to tens of thousands of people. The trials are randomized and the goal is to assess the safety of the drug in a large group of people. In a larger sample, there might a chance to observe certain rare side effects.
- Approval and Licensure: After the success of phase-3 trials the manufacturer approaches the drug authorities for the license to sell. Following this, the drug is administered to the population in a planned manner taking into consideration the different age groups and the more vulnerable population.
We should note that we proceed into one stage only after successfully passing the previous stage. Without clearing the previous stages the drug cannot progress to the next stage.