Edward Jenner (1749-1623) was a GP (General Practitioner) from Gloucestershire, in the West of England. He was responsible for one of the most significant discoveries in preventive medicine. He found that smallpox a menace in those days could be prevented by vaccination. Jenner while he was a boy of six-years took keen interest in natural history, and decided to become a doctor. Edward began his studies under the surgeon named Ludlow, who in his practice treated a large number of country folk hailing from villages nearby. One day in 1766 he heard a dairymaid say that there was a lot of smallpox around in the village, but she was not afraid of it as she had already suffered cowpox, as dairymaids are very likely to catch it.

Jenner at the age of about twenty-one (1770) went to London for two years to study under John Hunter, a famous teacher of medicine. Shortly afterwards he returned to his village and took active part in founding the local medical society. In 1792 he took his degree of Doctor of Medicine of St. Andrews University, Scotland. While in London Jenner told Hunter that cowpox offered protection against smallpox. But Hunter looked upon it as mere superstition.

In about 1775 Jenner started making exhaustive notes of his cases to confirm the belief of the country folk that cowpox offers protection from smallpox. The only way to prove his belief was to produce cowpox in healthy persons, and observe whether it produced protection against smallpox. 

On May 14, 1796 Jenner inoculated a boy named James Phipps with matter taken from the cowpox blister from the hands of a dairymaid, and fortnight later he inoculated him with real matter from smallpox blisters. It was a rather bold thing to do. But he was right; the boy did not develop smallpox. On confirmation he wrote a treatise “Inquiry into the cause and effects of Variolae Vaccinae”. Jenner’s faith in his discovery was so implicit that he vaccinated his own son on three occasions.

Jenner had now achieved fame and the gratitude of thousands. He was presented to the King and Queen, and the Royal Family helped to spread the good news that smallpox was at last conquered. In 1807 vaccination was made compulsory in Bavaria, in Denmark in 1810, in Sweden in 1814, and now most other countries in the World have followed. Almost three centuries after Jenner the World Health Assembly declared the world free of this disease on May 8, 1980. Ali Maow Maalin was the last person to have smallpox caused by variola minor. Maalin was a hospital cook in Morea, Somalia.