Eczema vaccinatum
| Eczema vaccinatum | |
|---|---|
| 8 month old boy developed eczema vaccinatum after acquiring vaccinia from a sibling recently vaccinated for smallpox. | |
| Specialty | Infectious disease, Dermatology |
| Symptoms | Severe vesicular and umbilicated skin rash, fever, facial edema, malaise, lymphadenopathy, scarring |
| Complications | Airway compromise, keratitis, scarring, secondary infection |
| Usual onset | 5–19 days after vaccinia exposure |
| Duration | Variable |
| Causes | Vaccinia virus infection in people with atopic dermatitis or eczema |
| Risk factors | Past or present eczema, contact with recent smallpox vaccinee, filaggrin deficiency, young age |
| Diagnostic method | Clinical presentation; confirmed by PCR or viral culture |
| Differential diagnosis | Eczema herpeticum, impetigo |
| Prevention | Avoid vaccinia vaccines in atopic individuals or contacts |
| Treatment | Vaccinia immune globulin, antivirals (e.g., tecovirimat, cidofovir), supportive care |
| Prognosis | Variable; can be fatal if untreated |
| Frequency | Very rare (mainly after smallpox vaccination in atopic patients) |
| Deaths | Case fatality rate 1–6% (historically); up to 30% in infants |
Eczema vaccinatum is a rare severe adverse reaction to smallpox vaccination, caused by exposure to replicating live vaccinia virus.
It arises when vaccinia disseminates in people who have ever had atopic dermatitis or related eczematous disorders—or in their close contacts—because their impaired epidermal barrier permits unchecked viral spread.