Although no complete cure was ever found for people who had contracted the disease, a method of protecting people against catching it was discovered in 1796 by a doctor named Edward Jenner. He found that if he vaccinated people with the germs of a disease called cowpox (similar to smallpox but not nearly as dangerous), their bodies would develop an immunity which would prevent them from catching smallpox. This was a major step forward but did not lead to a dramatic decline in the spread of the disease throughout the world. Medical ideas spread slowly, communications were poor, the virus for vaccinations had to be developed carefully and there was resistance to the idea of vaccination. Even England, where vaccination had been discovered, suffered smallpox epidemics in 1893 and 1902. It was not until the 20th century that some countries began to overcome the disease by using improved vaccination viruses and better medical techniques. But then, as rapid air travel became possible, the problem worsened for travelers could swiftly carry the disease from country to country.