| 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[1] |
| Complications | Airway compromise,keratitis,scarring,secondary infection |
| Usual onset | 5–19 days after vaccinia exposure[2] |
| Duration | Variable |
| Causes | Vaccinia virus infection in people withatopic dermatitis or eczema[1] |
| Risk factors | Past or present eczema, contact with recent smallpox vaccinee, filaggrin deficiency, young age[1][3] |
| Diagnostic method | Clinical presentation; confirmed by PCR or viral culture[4] |
| Differential diagnosis | Eczema herpeticum,impetigo |
| Prevention | Avoid vaccinia vaccines in atopic individuals or contacts[1] |
| Treatment | Vaccinia immune globulin,antivirals (e.g.,tecovirimat,cidofovir), supportive care[5] |
| Prognosis | Variable; can be fatal if untreated[6] |
| Frequency | Very rare (mainly after smallpox vaccination in atopic patients) |
| Deaths | Case fatality rate 1–6% (historically); up to 30% in infants[6] |
Eczema vaccinatum is a rare severeadverse reaction tosmallpox vaccination, caused by exposure to replicating live vaccinia virus.
It arises whenvaccinia disseminates in people who have ever hadatopic dermatitis or relatedeczematous disorders—or in their close contacts—because their impaired epidermal barrier permits unchecked viral spread.[1]
The condition may be fatal if severe and left untreated.
Older, replicating vaccinia vaccines like ACAM2000 or the historic Dryvax should not be given to patients with a history of eczema. Because of the danger of transmission ofvaccinia, these also should not be given to people in close contact with anyone who has active eczema and who has not been vaccinated. People with other skin diseases (such as atopic dermatitis,burns,impetigo, orherpes zoster) also have an increased risk of contracting eczema vaccinatum. Third-generation smallpox/monkeypox vaccines currently used in public health programmes do not contain live replicating vaccinia and are therefore not subject to this warning.
Theincubation period from vaccinia exposure to rash averages 5–19 days.[2]
Because the vaccinee’sinoculation site may have crusted normally, clinicians must ask about any recent household contact with a vaccine recipient.[7] Physical examination typically reveals hundreds to thousands of monomorphic, umbilicatedpapules orpustules distributed over atopic skin, accompanied by fever and tender nodes.[1]
Mucosal or ocular involvement is infrequent but can precipitate airway compromise orkeratitis, as documented in adult case reports.[8]
Eczema is also associated with increased complications related to other vesiculating viruses such aschickenpox; this is calledeczema herpeticum.[citation needed]
A present or past diagnosis ofatopic dermatitis is the dominant risk factor, irrespective of current disease activity.[1]
Experimental models show thatFilaggrin deficiency—common in atopic dermatitis—facilitates systemic vaccinia spread, linking structural barrier genes to EV pathogenesis.[3]
First-time vaccinees and unvaccinated household contacts lackOrthopoxvirus immunity and therefore experience the most severe illness.[1]
Young children are disproportionately affected because both the prevalence of eczema and the risk of high-titerviraemia are greater at younger ages.[1]
EV is suspected when multiple vaccinia-type lesions arise outside the vaccination site in a patient with eczema or when such lesions follow close contact with a recent vaccinee.[4] Definitive confirmation relies on real-time PCR or culture to detect orthopoxvirus DNA from lesion material, differentiating EV from eczema herpeticum or bacterial impetigo.[7]
CDC surveillance criteria classify EV as a diffuse dermatological complication; confirmed cases must be reported throughVAERS to facilitate a public-health response.[9]
Eczema vaccinatum is a serious medical condition that requires immediate andintensive medical care. Therapy has beensupportive, such asantibiotics,fluid replacement,antipyretics andanalgesics, skin healing, etc.;vaccinia immune globulin (VIG) could be very useful but supplies may be deficient as of 2006. Severe or progressive illness unresponsive to VIGIV may be treated with anti-viral drugs, such asCidofovir orTecovirimat.[10][11] All three agents were used successfully in the 2007 Indiana child, marking the first paediatric use of cidofovir for vaccinia.[12]
Tecovirimat (TPOXX; ST-246) receivedFDA approval for smallpox in 2018 and is available under expanded-access protocols for EV, offering a targeted inhibitor with fewer renal toxicities than cidofovir.[5]
Supportive management (fluid resuscitation, meticulous wound care and airway protection) remains essential to reduce secondary sepsis and long-term scarring.[12]
In March 2007, a two-year-old boy and his mother in Indiana contracted the life-threateningvaccinia infection from his father who was vaccinated against smallpox as part of the standard vaccination protocol for individuals serving in theUS Armed Forces beginning in 2002. The child developed thepathognomonic rash which typifies eczema vaccinatum over 80 percent of his body surface area. The boy has a history of eczema, which is a known risk factor for vaccinia infection.[13]
Historical series place the overallcase-fatality rate at 1–6 percent, rising to about 30 percent in infants under two years.[6]