Q1.
Do you know when the first vaccine was discovered?
Answer
In the late 1700s, by the English doctor Edward Jenner.
Smallpox was a deadly disease that caused blisters and killed millions. A milder disease of cows called cowpox could also infect humans. Jenner discovered that people who had had cowpox did not get smallpox, and this led to the invention of the first vaccine.
The way he reached it is a model of scientific work:
| Observation | Milkmaids who had cowpox did not catch smallpox — likely because the two viruses are related |
| Hypothesis | Content in the pus of cowpox blisters protected people from smallpox |
| Experimentation | He injected cowpox sap into a boy, who later showed no illness when exposed to smallpox |
| Results | People infected with cowpox sap were now resistant to smallpox |
| Application | Mass vaccination eventually helped eradicate smallpox worldwide |
The graph on page 38 shows how completely this worked. The number of countries reporting smallpox fell from about 80 in 1950 to around 40 by the late 1960s, and then dropped steeply to zero. The vaccine campaign is marked at 1965 and eradication at 1979.
Our scientific heritage: long before Jenner, India had a traditional method called variolation. Material from a smallpox sore was used to scratch the skin, creating a mild infection that built immunity. The people who performed this practice were known as teekedaars.
Why it happens: the cowpox virus is closely related to the smallpox virus. The immune system, trained on the harmless relative, recognises the dangerous one when it arrives — which is the whole principle on which every vaccine since has been built.