Yes. You should know a few of the more serious complications related to vaccination that can occur. Inadvertent inoculation is the most frequent complication of vaccinia vaccination. It accounts for about half of all complications of primary (first) vaccination and revaccination. Inadvertent inoculation usually results from auto-inoculation of vaccinia virus, transferred from the site of vaccination. The most common sites involved are places that itch: the face, eyelids, nose, mouth, genitalia, and rectum.
Most auto-inoculation lesions heal without specific therapy, but vaccinia immunoglobulin (VIG) can help treat severe cases. If vaccinial keratitis develops, VIG is not recommended because of the risk of corneal scarring.
Erythematous or urticarial rashes can occur about 10 days after primary (first) vaccination and can be confused with generalized vaccinia. In these circumstances, the vaccinee is usually afebrile and the rash resolves spontaneously within 2 to 4 days. Rarely, an allergic reaction to to the vaccination called erythema multiforme (i.e., Stevens-Johnson syndrome), may occur.
The most serious complication is postvaccinial encephalitis. Two main forms were noted. The first affected children younger than 1 year old receiving their first (primary) smallpox vaccination, involving convulsions. These children may have residual paralysis after recovery.
The second form affected children 2 years or older, adolescents, and adults receiving their first (primary) smallpox vaccination. These patients developed abrupt onset of fever, vomiting, headache, and malaise, followed by loss of consciousness, amnesia, confusion, convulsions, and coma. About 1 in 3 of these patients died.