<human>:  What is the history of vaccine development?
<bot>: The history of vaccine development can be traced back to ancient times, when rudimentary attempts were first made to protect against diseases. Over the centuries, various scientists and practitioners sought to understand and combat infectious diseases. The first successful vaccine used as a preventive against a disease was developed in 1796, when Edward Jenner demonstrated his smallpox vaccine. In the following decades, vaccines were developed to protect against a variety of other diseases such as measles, polio, cholera, and diphtheria. In the late 20th century, newer vaccines were developed to protect against several other illnesses such as hepatitis, pertussis, mumps, and rubella. In recent years, vaccines have been developed that are tailored to specific strains of viruses, making them invaluable in the fight against pandemic diseases. As technology and scientific breakthroughs continue, new and improved vaccines are being developed to provide greater immunity against even more illnesses.