April 25, 2002
Dose Effects of Smallpox Vaccine
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The administration of undiluted vaccinia vaccine led to vesicle formation in 19 of 20 healthy volunteers. With a 1:10 dilution, the success rate was 70 percent. With a 1:100 dilution the success rate was only 15 percent. The appearance of vaccinia vesicles correlated well with vigorous cytotoxic T-cell responses and with interferon-
T-cell responses.
This study documents that the vaccinia vaccine produced in 1982 still has excellent potency but that dilution decreases the success rate. The formation of a vesicular skin lesion is an excellent indicator of the development of a protective immune response.
