Which was the very first vaccine ever developed?

Polio vaccines are vaccines used to prevent poliomyelitis. Two types are used: an inactivated poliovirus given by injection and a weakened poliovirus given by mouth. The World Health Organization recommends all children be fully vaccinated against polio. Smallpox vaccine, the first successful vaccine to be developed, was introduced by Edward Jenner in 1796-8. He followed up his observation that milkmaids who had previously caught cowpox did not later catch smallpox by showing that inoculated cowpox protected against inoculated smallpox. Td is a tetanus-diphtheria vaccine given to adolescents and adults as a booster shot every 10 years or after a presumed exposure in some cases, while Tdap is a similar vaccine that also contains protection against pertussis. A single dose of Tdap is recommended for children at the 11- to 12-year-old checkup. One dose of the MMR vaccine is about 97% effective at preventing rubella. Children may also get MMRV vaccine, which protects against measles, mumps, rubella, and varicella (chickenpox). ... CDC recommends that children get two doses of MMR vaccine. #immunology #vaccine #polioVirus #cowpox #smallpox #tuberculosis #Polio #Rubella #tetanus