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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