The history and testing of vaccinations
The COVID-19 vaccine was approved in late 2020. Now, 15 months after the first confirmed case of the coronavirus disease in the UK, a BBC article recently stated that nearly two thirds of the UK adult population have been vaccinated (approximately 34 million people).
But, what do we know about vaccinations and how have they developed over time?
What are they? A simplistic definition of the word ‘vaccination’ is an injection that stops you getting an illness. World Health Organization (WHO) states that vaccines save millions of lives each year and they work by training and preparing the body’s natural defences – the immune system – to recognise and fight off the viruses and bacteria they target. Following a vaccine (which typically contains a severely weakened virus or inactive parts), the immune system responds to the germs and creates antibodies so that if the body is exposed to the same germs in the future, it can protect itself.
When did they start? Some sources acknowledge that the history of vaccinations dates back in the Eastern world to around 1000 CE. Some of the historical essential details of disease prevention are not savoury, for example early Chinese and Indian inoculation against smallpox involved grinding up smallpox scabs and blowing the material into another person’s nostrils, but developed vaccinations have proved to work. In 1796 British doctor, Edward Jenner, became the founder of vaccinology (the science of vaccine development). Jenner’s experiments with cowpox against smallpox launched vaccination as a public health tool and his method was ‘arm-to-arm inoculation’. He took substance from a blister of a person infected with cowpox and placed it into a different person’s arm, bringing on an immune response which would ultimately provide future protection against the infectious disease.
Over the following 200 years, scientific knowledge advanced and large-scale mass production of vaccines was achieved, leading to the immunisation against smallpox by the 20th century.
How have they helped? It is widely recognised that vaccines have helped to reduce mortality rates. WHO states that immunisation currently prevents 4-5 million deaths every year. In the late 1940s, three vaccines were combined to become the recommended DTP vaccine, protecting against the fatal diseases: pertussis (whooping cough), diphtheria and tetanus. It has been said that due to the success of recommended vaccines and immunisation schedules, childhood diseases had almost disappeared from developed countries by the late 70s and WHO’s Expanded Programme on Immunization for Developing Countries (EPI) brought vaccinations against six diseases to more children, significantly improving public health problems. The six diseases were diphtheria, polio, tuberculosis, pertussis, measles and tetanus.
In 1980, following WHO’s twenty-year vaccination campaign, smallpox was eradicated. It is estimated that 300 million people in the 20th century were infected before its eradication. A more recent public health success might be the eradication of wild poliovirus due to the polio vaccine. Developed in 1950 in the US, the polio vaccine was used in different countries and 30 years later, a global effort to eradicate the disease was underway. According to WHO, in August 2020 the African continent joined all other parts of the world (except Pakistan and Afghanistan) and was certified as wild poliovirus free.
How are they tested? A vaccine and vaccine tests must meet demanding authority regulations before approved for use. The initial testing uses individual cells in a laboratory (known as ‘in vitro’ testing) and then the testing is done inside a living organism (known as ‘in vivo’). After a vaccine proves to work in animals, the testing can move on to phase testing. It seems that there are three main trial phases before licensing, which could be broken down as: Initial phase: up to 100 people tested and an effective dose is determined Consistent phase: checking consistency and immune response (including side effects) Data phase: gathering statistics and evidence of immunity Once the vaccine is at the phase’s stage of testing, the number of people tested increases dramatically with testing on several thousand people by the data phase. Once approved for use, there is a continual review of the vaccine on an ongoing basis. As well as meeting international regulatory bodies, for trials in the UK the Medicines and Healthcare products Regulatory Agency (MHRA) must give individual approval.