MARSHFIELD, WIS—As smallpox vaccination has been selectively resumed, physicians have had to refamiliarize themselves with the associated risks. Among persons with a history of atopic dermatitis (AD) or eczema, the primary concern is eczema vaccinatum, a localized or generalized cutaneous dissemination of the vaccinia virus that is typically mild and self-limiting, but that can be severe or fatal, especially in young children. The Advisory Committee on Immunization Practices thus recommends against smallpox vaccination in patients who have had either AD or eczema (or in their household contacts) unless smallpox exposure has occurred.

Yet a recent study raises more concerns. Allison Naleway, PhD, and colleagues have shown that one third or more of patients with eczematous skin disease do not recall ever being given a diagnosis of AD or eczema—even when the diagnosis was made within the past few years.[1] Dr. Naleway says this finding puts into question the validity of smallpox screening tools that rely only on a patient’s self-reported history.

Using a recognized diagnoses and procedures tracking system, the researchers established the prevalence of AD and eczema in a large, mostly rural population in North-Central Wisconsin. They identified 419 patients who had been given either diagnosis in 2000 or 2001 on two or more occasions separated by at least 60 days. Their resulting calculations showed that the prevalence rate for active AD and eczema was similar for males and females (respective means, 0.7% and 0.9%) and highest among children younger than 5 (mean, 2.8%). Based on an overall prevalence rate of 0.8% and an average household size of three, the researchers estimated that preexposure smallpox vaccination would be contraindicated in at least 2.4% of the residents of their community.

To ascertain how accurately people report a history of AD, the researchers conducted a telephone survey of 404 adult residents of their community; 94 of the participants had been given a diagnosis of AD at least twice since 1979, and the other 310 lived in a household with someone who had been given such a diagnosis. For the purposes of blinding, participants were queried about a number of immune-related medical conditions (including asthma, hay fever, and food allergies), not just about dermatologic diagnoses.

The results were surprisingly poor. Among the participants with a past diagnosis of AD, only 59% accurately recalled it, even when the question was broadly worded (eg, “Have you ever had atopic dermatitis, eczema, or an itchy rash that was coming and going for at least six months?”). Recall rates were 60% and 70%, respectively, for the interviews in which adults were asked about these diagnoses in an adult household member or in their children. The strongest predictor of poor recall was time since last diagnosis.

Recall might be better in the context of impending smallpox vaccination, Dr. Naleway said. In this setting, she explained, “potential vaccine recipients would be provided with educational material,” and they “might take a little more time to consider their past medical history and perhaps err on the side of caution,” reporting any condition they feel might put them at risk.

—Verna L. Schwartz, MS