The Demon in the Freezer
Richard Preston, 2002 (History, Reviews)

This is one of the scariest books I've read in a long time—and it’s not fiction! Published in 2002, it chronicles the strange tale of Smallpox, its world-wide eradication, and the lingering threat of its return. Millions are alive today thanks to the efforts of D. A. Henderson (who received the Presidential Medal of Freedom in 2002), the World Health Organization, and an army of public health workers. Smallpox is probably the worst disease the human race has ever known, and now it’s gone—well almost… The demon lives on in at least two freezers, one at the CDC in Atlanta and one in Russia. But there is no way to know how many other caches exist. In a cruel twist of fate, the fact that smallpox no longer exists in the wild
makes it well suited for bioterrorism. It is the biological equivalent of an atom bomb. This New Yorker article by Preston summarizes the major themes of the book.
Addendum: The threat of Smallpox as a bioweapon or even a lab leak accident may not be as bad as once thought. There is a window of several days after exposure to receive effective treatment using a technique calledring vaccination. As long as we have a robust public health infrastructure and adequate supplies of vaccine we should be protected from the worst.