Despite often being seen as a relatively modern triumph of global pharmaceuticals, vaccines and vaccinations have a long history, which can potentially be traced back as far as the 10th century AD.
Smallpox was one of the deadliest infections in human history and the earliest attempts to provide immunity from the disease came from 10th Century Chinese doctors, who would deliberately infect people with material taken from people’s smallpox sores.
The idea at the time, long before we knew the effects of antibodies in the body, was that it would provide a mild effect, but also then provide the same protections that people who had suffered from smallpox had.
This concept was revised once we knew more about how smallpox works and led to the development of the cowpox-based smallpox vaccine by Edward Jenner in 1796, which was the first-ever vaccination.
Thanks to this vaccine, more modern variations and a coordinated campaign to eradicate the disease by the World Health Organisation, smallpox was eradicated in the 1970s.
With vaccination being incredibly important at the moment, learning how vaccines are made and why they have the effect they do can help whilst vaccine rollouts continue to ramp up.
How Do Vaccines Work?
The body has a range of protections against disease, from physical protections such as mucus, hairs and skin, to antibodies in our immune system.
They take a pathogen (any organism that causes disease) and produce antibodies that smother and stop the virus, as well as maintaining a memory in our body of the types of antibodies that worked to fight that particular pathogen so it can fight it again.
This is why the first time you are infected with a disease it can make you very ill, but the second time you may not even notice or have much milder effects, depending on whether it has mutated or changed, requiring new antibodies.
Vaccines aid this process by triggering the immune response in our body without the virus being there. In the past, this was done, like smallpox by having a weakened version of the disease be part of the vaccine, but modern vaccines have the blueprint for producing antigens directly.
This reduces the risk of side effects whilst still providing that level of protection.
The development of vaccines revolves around creating an active antigen component that creates an immune response, which depending on the vaccine is either a small part of the organism that triggers the response or a weakened version of the whole pathogen.
Developing vaccines to do this involves extensive research, screening, tests and evaluations to work out which antigen would trigger the immune response to the disease in question.
Once this is successfully found in a lab, it needs to be rigorously tested, first with a small group of volunteers to ensure it is safe, works and find the right dosage for the population (Phase 1 testing).
After this, a larger test of several hundred volunteers will be undertaken (Phase 2 testing), who have the same characteristics as the people who will want to take the vaccine (in the case of Covid-19, that is nearly everyone, but especially anyone considered clinically vulnerable).
This test is to ensure that the virus is safe in a wider demographic, try different formulations and blind test against a control group to ensure that the results were not found by chance.
Finally, there is a mass trial (Phase 3 testing), which tests thousands of people compared to the best current alternative.
Finally, with all of this information, there will also be rigorous reviews of safety and efficacy before they will be approved for use in the global population.
Even after this approval, further reviews will ensure the vaccine is safe in the long term and provides effective immunisation.