Two vaccine companies won $20 million in federal contracts Tuesday to speed development of a safer smallpox inoculation. Acambis Inc. of Cambridge, Mass., and Denmark’s Bavarian Nordic A/S are researching a smallpox vaccine that would be made with a modified version of the virus in today’s shots. Today, the only smallpox vaccine available isn’t safe for people with weakened immune systems, and can even seriously harm some healthy people, because it’s made with a live virus called vaccinia that can spread through the body. Scientists now are researching a modified strain of that virus that doesn’t replicate inside cells, and therefore shouldn’t pose such a risk. Full Story