Vaccine

Vaccination

Smallpox vaccine is unique in that it is not administered by injection, it’s administered with a two pronged, or bifurcated, needle into the superficial layer of skin. (19:15)

Vaccinia virus replicates in the basal cells of the epidermis, producing a papule surrounded by erythema 3 to 5 days after primary vaccination. A vesicle then forms, which becomes pustular by 7 to 11 days after vaccination. (19:16) A person is considered protected with the development of a pustule like this at the vaccination site.

Vaccinia virus is present at the vaccination site beginning 3 to 4 days after vaccination until the scab separates. Care must be taken to avoid transferring virus to other parts of the body, such as the eye, or to other people.

After about 3 days, a red papule appears at the vaccination site and becomes vesicular on about the fifth day. By the seventh day, it becomes the typical Jennerian pustule – whitish, umbilicated, multiocular, containing turbid lymph and surrounded by an erythematous areola that may continue to expand for 3 more days. Regional lymphadenopathy and fever is not uncommon. As many as 70% of children have 1 or more days of temperature higher than 39¾C (100¾F) between days 4 and 14. The pustule gradually dries, leaving a dark crust, which normally falls off after about 3 weeks. (9:8)

There was a 90% reduction in smallpox among contacts with a vaccination scar compared to contacts without a scar. Epidemiologic studies demonstrated that this high level of protection against smallpox persists for up to 5 years after primary vaccination and substantial but waning immunity can persist for ten years or more. Vaccination 30 or more years may not protect against smallpox, vaccinated people appear to have less severe disease.

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