Next-Generation Smallpox Vaccine Being Stockpiled in U.S.

A Danish company has delivered the first 1 million doses of a next-generation smallpox vaccine to the U.S. national stockpile, a vaccine reserved for people with weakened immune systems.

The federal government has ordered 20 million doses of Bavarian Nordic's Imvamune, a vaccine developed in part with U.S. research money as part of the nation's preparations in case of a bioterrorist attack.

The government has long stockpiled smallpox vaccine against such a possibility. But the conventional vaccine, made with a live virus that's a relative of smallpox, isn't safe for people with weakened immune systems. Imvamune is made of a different strain of the virus, targeted for the immune-compromised because it cannot multiply in human cells.