Definite clinical, histologic and immunologic changes take place following smallpox vaccination. After its full development on the ninth or tenth day, the vaccinial lesion is followed by drying, crusting and scarring. Histologically, there are degenerative and irritative changes in the epidermis believed to be due to the direct action of the virus on the epithelial cells. Immunologically, humoral antibodies to vaccinia begin to appear at the end of the first week following cutaneous vaccination, increase in amount during the second and third weeks and reach a maximum at the end of the third week. The probable reason for the involution of the vaccinial lesion after the pustular stage is the appearance of specific antibodies in the blood which apparently neutralize the vaccinia virus. The presence of histologically active vaccinial lesions approximately four months after implantation of the vaccinia virus could only be explained on the inability of the child to develop immunity to the vaccinia virus. Because of this lack of immunity, degenerative action of the vaccinia virus continued unopposed.

This content is only available via PDF.
You do not currently have access to this content.