Eczema vaccinatum: A common concern with smallpox vaccination involving the implantation of the vaccinia virus from the vaccination into the skin of a person with eczema (atopic dermatitis), sometimes with a fatal outcome. Disrupted skin permits viral implantation. Once the virus is implanted, it spreads from cell to cell producing extensive lesions. The skin lesions appear identical to a primary smallpox vaccination. Confluent lesions often cover the entire face, the crook of the elbow in the antecubital fossa, and behind the knee in the popliteal fossa. Viremia (viral spread through the bloodstream) may also occur allowing for the spread of virus to other parts of the body, including skin that is not affected by eczema. Bacterial and fungal invasion may occur as a late stage of untreated eczema vaccinatum.
It is estimated that there are 27 million individuals in the US alone who have atopic dermatitis, many of whom would be susceptible to eczema vaccinatum if vaccinated or in contact with a vaccine. Further, it appears that even healed skin is not normal and eczema vaccinatum has occurred in the skin of such individuals at the sites of prior florid eczema.
The key to treatment is the use of Vaccinia Immune Globulin (VIG). With early recognition and appropriate use of VIG, mortality (the risk of death) can be reduced to zero, and morbidity alleviated. Bacterial and fungal invasion require antibiotic therapy.
To prevent eczema vaccinatum, vaccination should not be performed in patients with eczema and they should not be in contact with vaccines, if smallpox is not an immediate risk. However, if there is smallpox in the community with potential exposure, or if the patient is a household contact of a case, then vaccination must be performed.