Researchers say they've come up with an experimental smallpox vaccine that they think is safer than the traditional vaccination.
The preparation, known as MVA, has been shown in lab tests to provide effective protection for monkeys and mice against a pox virus.
A report on the monkey study is published this week in the journal Nature. A second study, in which mice were tested, is in the Proceedings of the National Academy of Sciences.
Scientists say the test proved that MVA is safer because monkeys injected only with that vaccine did not develop the sores and other side effects common in traditional smallpox vaccinations.
In the mouse study, MVA injections protected the animals against a lethal dose of vaccinia virus, a close relative of smallpox.