Public Release: 

Study shows low risk of vaccinia transfer after smallpox immunization

Infectious Diseases Society of America

The threat of bioterrorism has led to the recommendation to vaccinate health care workers and other first responders, but some worry about the side effects of smallpox vaccination, which can harm children, pregnant women and people with immune disorders or certain skin conditions. According to an article published in the February 15 issue of Clinical Infectious Diseases, now available online, people vaccinated against smallpox pose a low risk of accidentally inoculating others if they follow proper bandaging and hand-washing procedures.

Smallpox vaccinations leave an open wound on the upper arm containing a live virus that could infect others. If a child, a person with eczema or someone with an immune disorder is infected, the virus can cause serious health problems or death. Consequently, some hospitals decided that health care workers should not be vaccinated against smallpox to prevent accidental transmission of the virus to vulnerable patients.

"Hopefully, this study has helped reassure individuals about the transmission of smallpox," says lead author Thomas Talbot, MD, of Vanderbilt University Medical Center. The risk of transmission is vastly reduced if those vaccinated against smallpox keep the vaccine site bandaged and practice "good, thorough hand-washing with soap and water or an alcohol-based product" after changing the bandage, says Dr. Talbot.

Dr. Talbot sees no need for everyone to get vaccinated against smallpox, because civilian and military vaccination campaigns have created a safety net of sorts. "If someone were to intentionally release smallpox, we have our first wave of health care responders protected," he says. The vaccine can be administered as long as three to four days after exposure, so health care workers who have been vaccinated could "take care of patients and vaccinate everybody else" in the days following an attack, says Dr. Talbot.

Whether hospitals will change policies regarding vaccinations for health care workers based on the study's outcome remains to be seen. "It's been an interesting question, and hopefully now we've got a lot of contemporary data to help answer it," says Dr. Talbot.


Founded in 1979, Clinical Infectious Diseases publishes clinical articles twice monthly in a variety of areas of infectious disease, and is one of the most highly regarded journals in this specialty. It is published under the auspices of the Infectious Diseases Society of America (IDSA), based in Alexandria, Va., a professional society representing more than 7,500 physicians and scientists who specialize in infectious diseases.

Note: Interviews with Dr. Talbot can be arranged by contacting Diana Olson at or 703-299-0201.

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