The two-year-old boy from Indiana inadvertently contracted eczema vaccinatum from his father, a US soldier who had been deployed to Iraq, when he came into contact with the vaccination site. As the smallpox vaccine is made using a closely related live virus called vaccinia, the vaccine can cause severe side effects.
The patient developed late-stage manifestations of the disease, including hemorrhagic lesions, respiratory failure, shock and high viral loads in the blood. Although ST-246 has only been tested on animals due to the absence of the disease in the general human population, the FDA granted Siga an emergency investigational new drug application.
Doctors at the hospital where the child is being treated have said that following the treatment with ST-246 and other anti-viral agents, his health has started to improve. Development of ST-246 has been supported by grants from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, the CDC and the Department of Defense.