Fewer than 40,000 actually received the vaccine.On April 21, 2022, Public Services and Procurement Canada published a notice of tender seeking to stockpile 500,000 doses of smallpox vaccine in order to protect against a potential accidental or intentional release of the eradicated virus. On May 6, the contract was awarded to Bavarian Nordic for their Imvamune vaccine. These were deployed by the Public Health Agency of Canada for targeted vaccination in response to the 2022 monkeypox outbreak. Origin
The origin of the modern smallpox vaccine has long been unclear, but horsepox was identified in the 2010s as the most likely ancestor. : 9  Edward Jenner had obtained his vaccine from a cow, so he named the virus vaccinia, after the Latin word for cow. Jenner believed that both cowpox and smallpox were viruses that originated in the horse and passed to the cow,: 52–53  and some doctors followed his reasoning by inoculating their patients directly with horsepox. The situation was further muddied when Louis Pasteur developed techniques for creating vaccines in the laboratory in the late 19th century. As medical researchers subjected viruses to serial passage, inadequate recordkeeping resulted in the creation of laboratory strains with unclear origins. : 4  By the late 19th century, it was unknown whether the vaccine originated from cowpox, horsepox, or an attenuated strain of smallpox.In 1939, Allan Watt Downie showed that the vaccinia virus was serologically distinct from the "spontaneous" cowpox virus. This work established vaccinia and cowpox as two separate viral species.
The smallpox vaccine is the first vaccine to be developed against a contagious disease. In 1796, the British doctor Edward Jenner demonstrated that an infection with the relatively mild cowpox virus conferred immunity against the deadly smallpox virus. Cowpox served as a natural vaccine until the modern smallpox vaccine emerged in the 20th century. From 1958 to 1977, the World Health Organization (WHO) conducted a global vaccination campaign that eradicated smallpox, making it the only human disease to be eradicated. Although routine smallpox vaccination is no longer performed on the general public, the vaccine is still being produced to guard against bioterrorism, biological warfare, and monkeypox.The term vaccine derives from the Latin word for cow, reflecting the origins of smallpox vaccination. Edward Jenner referred to cowpox as variolae vaccinae (smallpox of the cow). The origins of the smallpox vaccine became murky over time, especially after Louis Pasteur developed laboratory techniques for creating vaccines in the 19th century. Allan Watt Downie demonstrated in 1939 that the modern smallpox vaccine was serologically distinct from cowpox, and vaccinia was subsequently recognized as a separate viral species. Whole-genome sequencing has revealed that vaccinia is most closely related to horsepox, and the cowpox strains found in Great Britain are the least closely related to vaccinia. Types
As the oldest vaccine, the smallpox vaccine has gone through several generations of medical technology. From 1796 to the 1880s, the vaccine was transmitted from one person to another through arm-to-arm vaccination.