In 1796, the scientist Edward Jenner injected material from a cowpox virus into an eight-year-old boy with a hunch that this would provide the protection needed to save people from deadly outbreaks of the related smallpox virus.

1796 年，科學家愛德華·簡納將牛痘病毒中的物質注射到八歲男童身上，並有預感此舉將能為致命的天花疫情提供預防方法，拯救民眾生命。