History of Smallpox Vaccination
The idea of intentionally inoculating healthy persons to protect them against infection dates back to the 6th century AD, when Chinese physicians mixed dried, powdered scabs from a smallpox victim with musk or other fragrances. The "vaccinees" had to insert a cloth containing that mixture into their nose. Another way of application was to blow this mixture into the nose by means of small tubes. In India, healthy persons tried to protect themselves by sleeping next to a smallpox victim or wearing the shirt of an infected person.
The first successful use of intentional inoculation in the Western world took place in 1717 on the children of the English ambassador to Constantinople. Giacomo Pylarini, a Greek doctor from Smyrna, was the first to introduce intentional infection by scratching the vein of a healthy person and pressing a small amount of matter, taken from a smallpox pustule of a person with a mild attack, into the wound. This early immunization effort was called "variolation". In 1721, Lady Mary Wortley Montagu (1689-1762), the wife of the British Ambassador to Turkey, brought this method to England. It is also reported that two sons of the British royal family were successfully variolated in London. Catherine the Great of Russia invited an English specialist to variolate her family members at the court in St. Petersburg.
The turning point in immunization efforts came when an epidemic of smallpox swept through the English county of Gloucestershire in 1788. One of the doctors involved in attempting to control the outbreak was a thirty-nine year old general practitioner called Edward Jenner (1749-1823). After training in London and a period as an army surgeon, Jenner spent his whole career as a country doctor in his native county of Gloucestershire in the West of England. His research was based on careful case-studies and clinical observation more than a hundred years before scientists could explain the viruses themselves. He observed that milkmaids who had contracted cowpox - now known to be an Orthopoxvirus similar to variola - had a lower incidence of smallpox infection. Unlike his other patients, they did not even produce the symptoms of a mild attack of smallpox. He had also noted that when whole families succumbed to smallpox, cowpox victims were unaffected and remained healthy.
The year 1996 marked the two hundredth anniversary of Edward Jenner’s first experimental vaccination, which was carried out on one of his patients called James Phipps, an eight year old boy. He made two cuts in the boy’s arm and worked into them a small amount of cowpox pus. Although the boy reacted with a slight fever, he recovered within several days. When, a few weeks later Jenner repeated the inoculation, using smallpox matter, the boy remained healthy. Vaccination treatment had been born.
Continuing with his experiments, Jenner reported his results to the Royal Society. They considered, however, that he should not risk his reputation by presenting something "so at variance with established knowledge". In 1798 Jenner published his work privately and within a few years the practice of vaccination proved instrumental in decreasing the number of smallpox deaths. For example, in the period 1899-1908, in countries with mandatory vaccination, the smallpox mortality rate ranged from 0.27 per million in Sweden to 91.08 per million in France, while in countries without mandatory vaccinations, the rate was considerably higher: 310.71, 394.08, and 567.28 per million in Greece, Spain, and Russia, respectively.
For his first smallpox vaccine, Jenner used bovine serum containing the cowpox virus. His innovation proved to be so successful that by 1840 the British government had banned alternative preventive treatments against smallpox. "Vaccination", the term Jenner coined for his treatment (from the Latin medical name for cowpox, vaccinia), was later adopted by Pasteur for immunization against any disease.
As more and more countries adopted mandatory vaccination, the number of countries with endemic smallpox decreased to 58 by 1957. However, even in countries without endemic smallpox, outbreaks initiated by the arrival of an infected person from abroad were not uncommon.
Smallpox vaccines of the first generation contain live vaccinia virus, a virus closely related to the variola virus. Immunity resulting from vaccination with vaccinia virus protects against smallpox. Although no clinical studies exist on the duration of protection, the WHO estimates that vaccination usually prevents smallpox infection for at least ten years.
Vaccination against smallpox is possible for up to 3-4 days after exposure, thus leaving some additional time for preventive measures to be implemented.