<human>:  What was the first vaccine?
<bot>: The first vaccine was developed in 1796 by Edward Jenner. It was a vaccine against smallpox. Smallpox is a highly contagious disease that causes fever, rash, and blisters. It is spread through contact with infected people or objects. The vaccine was made from a smallpox scab, which was taken from the skin of a person who had smallpox. The vaccine was used to prevent smallpox, and it was very effective.