Vaccine reactions and the use of immune globulin
Most deaths from encephalitis, progressive vaccinia
According to materials distributed at the smallpox working group meeting recently held by the Centers for Disease Control and Prevention (CDC), reactions to smallpox vaccine range from mild to moderate to severe. (See charts.)
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Details about these reactions include:
Historically, people being vaccinated for the first time (primary vaccinees) experienced adverse reactions at higher rates (>/ 10x) than those being revaccinated; rates are higher in infants than in older children or adults. Inadvertent inoculation at other sites is the most frequent vaccine complication, accounting for nearly half of all complications of primary vaccination and revaccination. Most lesions heal without therapy; vaccine immune globulin (VIG) may be useful for cases of ocular implantation.
Progressive vaccinia, a potentially fatal complication of vaccination, has occurred almost exclusively among immunocompromised people. Approximately 15% to 25% of vaccinees who develop post-vaccinal encephalitis die, and 25% have permanent neurological sequelae. Most deaths caused by vaccination are the result of post-vaccinal encephalitis or progressive vaccinia: approximately one death/million primary vaccinations and 0.25 deaths/million revaccinations.
Approximately 5% to 20% of vaccine adverse events occur in the contacts of vaccine recipients. Inadvertent inoculation is the most frequent adverse event occurring in contacts of vaccines (60%). In the 1963 and 1968 national surveys, approximately 20% of VIG recipients were contacts; most frequently with eczema vaccinatum. Eczema vaccinatum can be more severe in contacts than in actual vaccine recipients.
Based on the data from the 1963 and 1968 state and national surveys, it appears that at least 10 times more mild adverse events (including mild eczema vaccinatum, generalized vaccinia, and inadvertent inoculation) occur than events that need VIG. Generalized vaccinia, vaccinia necrosum, eczema vaccinatum, and some accidental implantation can be treated with VIG. CDC has developed estimates of the frequency of adverse events requiring VIG therapy as a basis for establishing a stockpile.
In addition, vaccination would result in — 0.5 to one death per million persons vaccinated — primarily from post-vaccinal encephalitis, which cannot be treated with VIG.
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