HealthDay News — The potential exists for further transmission of vaccinia virus beyond the direct sexual contacts of smallpox vaccinees, researchers found.

Hai Shao, MD, PhD, from the Scripps Mercy Hospital in San Diego, and colleagues described the epidemiology and clinical course of the secondary and tertiary cases in the CDC’s Morbidity & Mortality Weekly Report in efforts to prevent further transmission to contacts.

The smallpox vaccine had been administered under the U.S. Department of Defense smallpox vaccination program. While the vaccinee did not experience vaccine-associated complications, a male with whom he had sexual intercourse during the 2- to 30-day post-vaccine period during which vaccinia transmission is possible, presented with a painful perianal rash and a lesion on his upper lip, as well as fever, malaise, nausea and vomiting, and a history of eczema.

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The patient with secondary infection reported sexual intercourse with another male partner, following presentation of his rash, but prior to his hospitalization. This male, too, sought medical attention (two days following intercourse) for malaise, papular penile lesions and a lesion on his forearm.

Both patients were hospitalized and received vaccinia immune globulin intravenous. Their lesions healed without complications.

“This case report is the first reported instance of tertiary vaccinia transmission through sexual contact,” Shao and colleagues wrote.

No further transmission of vaccinia virus by the smallpox vaccinee or the secondary or tertiary patient has been reported.

“The illness experienced by the two patients and the potential for further contact transmission underscores the importance of smallpox vaccinee compliance with covering the inoculation site and instruction regarding the particular hazards of vaccinia transmission to genital and perianal areas,” the researchers wrote.


  1. Centers for Disease Control and Prevention. MMWR. Morb Mortal Wkly Rep. 2013;62(08);145-147.