Tuesday, May 26, 2009

ST-246 and eczema vaccinatum

A follow-up to our discussion today in class, and to Cooper’s post, “Smallpox vaccine and Eczema,” below!

A 2-year-old boy in the US came down with eczema vaccinatum, a life-threatening reaction to live vaccinia virus, in March 2007. Reactions to vaccinia (as we’ve learned) are usually not serious, but can become so in immunocompromised patients or, as in this case, in patients with eczema. Symptoms of eczema vaccinatum are very similar to smallpox (see picture).

After he was diagnosed (doctors had to rule out herpes and chickenpox, and conduct PCR tests to confirm presence of a poxvirus), the boy was injected with vaccinia immune globulin. When his condition worsened, they added cidofovir —which is actually licensed to treat cytomegalovirus, but can be used in emergencies for vaccinia complications. Cidofovir didn’t seem to work, either. Because the boy’s condition was life-threatening and growing worse, doctors decided to try ST-246, a new, experimental drug—and the boy slowly started to improve. ST-246, as we discussed in class, is an orally active drug inhibiting viral replication for multiple poxviruses.

It’s unclear what actually saved the boy, since he was receiving three different drugs and a variety of other care. The article says that blood samples weren’t able to pinpoint the exact time at which the boy’s viral levels dropped. But, it appears that ST-246 may have been a significant part of his recovery, and deserves further research.

The case raises a lot of questions about current smallpox vaccination policies. The boy was exposed to vaccinia through his father, a soldier stationed in Iraq, who had received the smallpox vaccine. Although public vaccination ended after 1979 and military vaccination after 1990, Bush re-started military vaccination in 2002. Whether or not the benefits of military vaccination outweigh the risks is a continuing subject of debate. And technically, this soldier (at least) should have been screened out of vaccination because of his son’s condition.

Although doctors and public health agencies worked well together to save the boy, the overall handling of the situation doesn’t bode well for a real smallpox epidemic: if it had been smallpox, say experts, the slow speed at which the health system rallied to action means that many more people would have been infected and killed.

Here's the Science mag article,


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