Narrator: This is Science Today. Recent events have linked biological warfare and anthrax in the minds of most Americans. But smallpox could pose a far greater danger. George Rutherford, head of the University of California, San Francisco's Preventive Medicine and Public Health Division, says that after a vaccine wiped out the highly infectious disease in the 1970s, many people believed it was no longer a threat.Rutherford: Which is completely and absurdly wrong. This assumes that 100 percent of the population is immune to smallpox. The correct number for that is zero percent.
Narrator: The vaccine only protects for about twenty years and the United States stopped vaccinating civilians thirty years ago.
Rutherford: Basically, nobody's immune anymore. The U.S. has 15 million doses stored. There's a real worry that they've outdated. There are currently randomized, controlled trials going on in St. Louis trying to see if a half-dose of smallpox vaccine will be equally as protective as a full dose of smallpox vaccine just as a way to double the number of doses available.
Narrator: For Science Today, I'm Larissa Branin.