How is smallpox vaccine made?
The vaccine against smallpox was the key tool in the eradication of the disease. The vaccine does not contain the variola virus, which causes smallpox, but a closely related live virus called vaccinia (VACV). When this vaccine is given to humans, the resulting immunity protects them against smallpox. Most existing vaccine stocks and the vaccine used in the WHO eradication campaign consist of pulp scraped from vaccinia-infected animal skin, mainly calf or sheep, with phenol added to a concentration sufficient to kill bacteria but not so high as to inactivate the vaccinia virus (VACV). The vaccine is then freeze-dried and sealed in ampoules for later re-suspension in sterile buffer and subsequent intradermal inoculation by multiple puncture with a bifurcated needle. A number of strains of seed virus have been used to produce smallpox vaccine, one of these the New York City Board of Health strain (NYCBH) of VACV substantially contributed to the global eradication of the disease. During th
