Smallpox was a disease feared since the dawn of written history (the earliest records are from Egyptian mummies more than 3500 years ago),occurring worldwide independent of climate, highly contagious and it was a disease virtually everyone acquired. Its onset was usually 1 to 3 weeks following exposure and severe symptoms were high fever, followed by the development of ugly, painful pustules all over the body. Patients had difficulties eating and drinking due to pustules inside the oral cavity. Complications were severe scars all over the body and blindness. The mortality was between 15%and 30% and there was no treatment. It is estimated that in the 20st century alone 300 million people died from smallpox. This is more than twice the death toll of all of military wars in the same time period.
In 1796 the English country physician Edward Jenner, discovered that milkmaids did not develop smallpox, because they acquired from cows an an infection of their hands that caused pustules resembling small pox. Jenner took material from such a pustule and scratched it into the skin af a small boy .The boy developed a single pustule, but was not ill. Six weeks later Jenner showed that the boy was protected from smallpox. This was the world's first vaccination. The cow pox was a caused by a similar virus than smallpox and by inoculating this materia,l the boy's immune system developed immunity against smallpox as well.
Progress in vaccination larger populations was very slow, especially early vaccines were only effective 2 – 3 days at room temperature. Production in large scale and distribution was difficult, never the less in the developed countries health services and communication were improving and many could be vaccinated and most of these countries maintained national vaccination programs. Not until the 1950-ies, methods to produce large quantities of heat stable vaccins were perfected and production could be set up in tropical areas. However it took a monumental effort of the World Health Organization (WHO) to decide on and execute a world-wide smallpox vaccinating and tracing/isolating program to eradicate the diease. The decision was taken in 1966 with only a few votes majority by the WHO general assembly. In the following 11 years health care workers surmounted formidable challenges on all levels: organizational, political, religious, geographical and cultural. Finally after the last case was observed in October 1977 in Somalia and afterwards for two years there was no further case worldwide, on May 8 1980, the 33rd WHO Assembly in Genva could declare smallpox as eradicated “ …the world and all its people have won freedom from smallpox…. A most devastating disease….. since earliest time, leaving death, blindness and disfigurement in its wake and which only a decade ago was rampant in Africa, Asia, and South America.”
Source: Henderson DA (December 2011)."The eradication of smallpox – an overview of the past, present, and future". Vaccine. 29 Suppl 4: D7–9. doi:10.1016/j.vaccine.2011.06.080.PMID 22188929