Close Monitoring Important to Reduce Risk of Adverse Effects from Large-Scale Smallpox Vaccination

CHICAGO — In a commentary in the October 16 issue of The Journal of the American Medical Association (JAMA), smallpox experts outline the potential risks associated with large scale vaccination against the smallpox virus.

CHICAGO — In a commentary in the October 16 issue of The Journal of the American Medical Association (JAMA), smallpox experts outline the potential risks associated with large scale vaccination against the smallpox virus.

The authors write, “The available data from the 1950s and 1960s show that there is a risk of vaccinia transfer from a primary vaccinee to an unimmunized individual in contact with the vaccinee, but the risk is not large. This risk needs to be kept in perspective. The U.S. studies indicate that transfer of vaccinia virus from contacts that resulted in EV (eczema vaccinatum – a severe skin rash) occurred at a frequency of about 1 to 2 per 100,000 primary vaccinations, and the overall transmission of contact vaccinia occurred in the range of 2 to 6 per 100,000 primary vaccinations,” the authors report. The authors note that “in all of the studies, contact vaccinia required close contact, was an unusual occurrence outside of the home, and occurred rarely as a result of hospital-related contact.”

The authors note that it is impossible to predict the likelihood of adverse events. However, they indicate that there are more people with eczema and other skin conditions and compromised immune systems than there were in the 1960s who may be more susceptible to adverse reactions to a smallpox vaccine. The authors conclude, “An orderly, systematic approach along with careful screening to identify potential vaccinia-susceptible individuals and household contacts and close monitoring for adverse effects are essential to reduce the risk of transmission of vaccinia following smallpox vaccination.”

The commentary is authored by John M. Neff, M.D., Center For Children With Special Needs, Children’s Hospital & Regional Medical Center, and the University of Washington School of Medicine, Seattle; J. Michael Lane, M.D., M.P.H., formerly of the Smallpox Eradication Program at the Centers for Disease Control and Prevention, Atlanta; Vincent A. Fulginiti, M.D., of the University of Arizona School of Medicine, Tucson; and Donald A. Henderson, M.D., M.P.H., of Johns Hopkins University Center for Civilian Biodefense Strategies, Baltimore.
(JAMA. 2002; 288: 1901 – 1904. Available at

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