Why is a vaccine called a vaccine?

Answer 1

The words vaccine and vaccination were made up by Edward Jenner who experimented with vaccines including the smallpox vaccination in 1790 which could be prevented from occurring with a mild version of cowpox pus, instead of the virulent and dangerous smallpox pus used before Jenner's work for more than 4000 years in the smallpox inoculation that sometimes caused smallpox instead of preventing it and could even kill the recipient. The word vaccination derives from the Latin word vacca meaning cow. Later vaccines (e.g. rabies, MMR, tuberculosis, polio, canine distemper, canine parvovirus, infectious canine hepatitis, adenovirus-2, leptospirosis, bordetella, canine parainfluenza, anthrax, plague, Lyme disease, flu) have nothing at all to do with cows, but the name "vaccine" stuck.