a lasting vaccine
by Cate House

efore 9-11 most of us didn't give much thought to smallpox. Not since 1972 have people been routinely vaccinated. Americans believed that the smallpox virus had been eradicated. But with the threat of bioterrorism comes a heightened fear of smallpox as well as a concern over how to best handle the limited supply of vaccine.

Jeffrey A. Frelinger, Kenan professor and chairman of microbiology and immunology, may have some insight. Frelinger and postdoctoral researcher Lawal Garba found evidence that the smallpox vaccine containing the vaccinia virus and routinely given to infants until 1972 has a longer immunity than researchers had thought.

The researchers tested blood samples from 13 subjects, four of whom had been vaccinated for smallpox within the past five years and nine of whom had older vaccinations up to 35 years prior. They tested each individual's CD8 T cell response (CD8 T cells are white cells that kill other body cells that have been infected by a foreign organism) to vaccinia exposure.

he researchers found that all of the subjects had a strong immune response to the vaccinia, although those with older vaccinations did have a slightly lower level of interferon-gamma (the molecule produced by CD8 T cells to protect against viral infection). Until now, researchers had believed that the vaccinations lasted only seven to ten years, although some studies suggested that partial protection could last more than 50 years.

Because vaccinating all Americans would be expensive and dangerous — side effects of the smallpox vaccine include fever, muscle soreness, large skin infections, and even death — Frelinger suggests vaccinating doctors, nurses, and emergency workers — those who would be the first to respond to an outbreak.

This research was published in the August 29, 2002, issue of The New England Journal of Medicine. A larger study by the National Institutes of Health is investigating the longevity of the smallpox vaccine.

Cate House is a freelance writer and staff writer for Carolina's Office of University Development.
[Email Cate House.]

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