Children Vaccines

Smallpox Vaccines

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Vaccinia virus is the live poxvirus that was used as the smallpox vaccine. The development of this vaccine was an important step in the successful eradication of smallpox, an infection characterized by fever, rash and constitutional symptoms, with a high rate of morbidity and mortality. Attempts at control of smallpox began after it was noted that accidental exposure to smallpox by a scratch on the skin reduced the severity of infection. This led to the practice of “variolation”, which involved intentional administration of pustular fluids from smallpox scabs to uninfected persons. The practice of variolation began in China and India in the tenth century; deaths were reported as a complication of this procedure. The origins of vaccinia virus are uncertain. Successful vaccination was highly protective for development of any disease for five years and could protect from death or severe smallpox for up to 20 years. Periodic revaccination was necessary for optimal protection.