Monthly Article: May - The Story of Immunization
The story of immunization is closely linked to the story of smallpox, a scourge that ‘struck down populations like bedbugs’ in the earlier centuries. The disease is estimated to have killed an estimated 400,000 Europeans each year during the eighteenth century. During the twentieth century, smallpox is estimated to have caused the death of almost 300–500 million people. But the story of smallpox is also the story of the success of immunization, which makes it unique. It is, in fact, the only infectious disease that has been totally eradicated.
That an attenuated form of the virus (variola) could offer immunity against the disease was known as early as 1000 BC. In India and China smallpox was prevented either through nasal insufflation of powdered smallpox scabs, or through variolation, which involved scratching material from a smallpox lesion into the skin. However, there was no guarantee that it would work, and sometimes the consequent attack could prove fatal. But variolation had a mortality rate considerably less than that of the disease itself.
Though the relation between cowpox and smallpox was probably fairly widely known in the countryside, it was Edward Jenner who first scientifically established the link between contracting cowpox and immunity from smallpox. The story goes that, in 1762, when he was thirteen years old, he was apprenticed to a country surgeon and apothecary in Sodbury, near Bristol. Here, Jenner heard a dairymaid say, “I shall never have smallpox for I have had cowpox. I shall never have an ugly pockmarked face.” But it was only in May 1796 that he extracted the cowpox virus from fresh lesions on the arm of a young dairymaid, Sarah Nelms, to inoculate an 8-year-old boy, James Phipps. He inoculated the boy again in July 1796, with matter from a fresh smallpox lesion. When the boy did not contract the disease, he concluded that the protection was total. (In fact, the term vaccination is derived from vacca, which means cow.)
When in 1797 Jenner sent his findings to the Royal Society, there were no takers. But things changed and by 1800 - vaccination against smallpox was widespread in England and had also reached Europe, in part an outcome of Jenner’s relentless promotion of vaccination. But it would take two centuries and more for the disease to be eradicated.
On May 8, 1980, the World Health Assembly announced that “The world and all its people have won freedom from smallpox, which was the most devastating disease sweeping in epidemic form through many countries since earliest times, leaving death, blindness and disfigurement in its wake.”
Today all known stocks of smallpox have been destroyed or transferred to one of the two WHO reference laboratories, the Centers for Disease Control and Prevention (CDC) in the United States and the State Research Center of Virology and Biotechnology Vector in Koltsovo, Russia, where troops guard it. Though WHOs initial plan was to destroy all existing virus stocks, the decision has been endlessly deferred in the interest of scientific research to develop new vaccines, antiviral drugs, and diagnostic tests. But in the face of threats of a biological warfare, the stocks have to be stored under the tightest security.