Since the invention of the smallpox vaccine, vaccines have greatly reduced the prevalence of diseases everywhere in the world.
This chart via Our World in Data shows a timeline of innovation in the development of vaccines. Each bar begins in the year in which the pathogenic agent was first linked to the disease and the bar ends in the year in which a vaccination against that pathogen was licensed in the United States.
For some diseases there has been a relatively short timespan between when the infectious agent was linked to the disease and when a vaccine was developed. For others, much longer. Malaria has proven to be the hardest as it has been over a century since the agent was linked to the disease.
Before 2020 the quickest development was that for measles – 10 years. In 2020 this record was broken when several vaccines were developed within just one year to fight the coronavirus pandemic.