A Brief History of the Prevention of Infectious Diseases.
Before the introduction of vaccines, people could only become immune to an infectious disease by contracting the disease and surviving it. Smallpox (variola) was prevented in this way by inoculation, which produced a milder effect than the natural disease. The first clear reference to smallpox inoculation was made by the Chinese author Wan Quan (1499–1582) in 1549.
Until the 1880s vaccine/vaccination referred only to smallpox, but Louis Pasteur developed immunization methods for chicken cholera and anthrax in animals and for human rabies, and suggested that the terms vaccine/vaccination should be extended to cover the new procedures.
But ever since the invention of vaccines, there has, for various reasons, also been a reluctance or refusal in parts of the population to be vaccinated or to have one's children vaccinated against contagious diseases despite the availability of vaccination services.
At the end of 2020 a vaccine against Covid 19 has finally been developed with a number other promising vaccines also in development. Let's hope that this will mark the start of the end of this terrible pandemic!