Memorable Shot: Smallpox vaccine has lasting effect

The threat that the smallpox virus could be used by terrorists as a biological weapon has become a cornerstone of modern angst. Now, a research team finds reason to assuage some of that anxiety: People vaccinated against smallpox decades ago retain significant antibody and immune-cell responses against the dangerous virus.

“We’re finding long-term immunity,” says Mark Slifka of Oregon Health and Science University in Beaverton.