Within a century of its mass production and spread, the concept of immunisation has become virtually the most necessary resource for any person after air, water, food and shelter. So important was its discovery that the American Centers for Disease Control and Prevention named active immunisation/ vaccination as one of the “Ten Great
Public Health Achievements in the 20th Century”.
Immunisation, as it is commonly known, is any method of “training” the immune system to recognise and fight off potentially harmful diseases. The different methods are largely classified under two categories: Active immunisation and Passive immunisation.
Active immunisation involves the exposure of the immune system to the microbe in order to “teach” it to produce the specific antibodies. This happens naturally, like in the case of chicken pox, where the immune system learns to produce antibodies against the disease the first time, and a second case is very rare. But immunisation against most diseases is brought about by introducing pre-treated or a milder version of the disease so as to train the immune system safely, without being affected by the disease. One of the most famous examples is the Poliovirus vaccine, where the virus strain is passed through non-human cells to deactivate them, before being administered orally to children.
Passive immunisation, however, involves the direct introduction of the particular antibodies in the body. In this case, the disease is fought off, but the effects are shortterm, and the disease can recur as the immune system did not produce the antibodies in the past.
The idea of introducing a weaker form of the disease to combat the same was unheard of in the 17th and 18th centuries, save for a few isolated groups. This makes sense, as medical science had not yet understood how the immune system functioned. Thus, it took centuries of smallpox epidemic breakouts to force medical practitioners to focus on a way to beat the disease. Edward Jenner was one among them, and he got his breakthrough in 1796, when he inoculated a child with cowpox, a similar and milder form of the variola virus that caused smallpox. This differed from the previous method of inoculation obtained from China in the early 1700s, known as „variolation‟. This risky
method involved taking smallpox virus from a patient and giving it in limited doses to a healthy patient, where only chance dictated whether the immune system could defend itself.
However, with the discovery of the smallpox vaccine, the science of vaccination had become established, as scientists went on to implement the same principle to all other previously incurable diseases. Today, we have come a very long way, having completely eradicated smallpox, and doing the same to polio too. Moreover, with the
enhanced technology of our times, we can analyse the virus/bacteria directly through genome mapping to deduce what antibody type the immune system must produce in order to tackle the disease. This landmark discovery in the human evolution is marked by celebrating „Immunisation week” annually between 24th to 30th April.