In 2008, the U.S. military shifted its vaccine stock from freeze-dried Dryvax vaccine produced by Wyeth in the 1970s and early 1980s to Acambis's ACAM2000 vaccine. Both vaccines use vaccinia virus, a virus related to cowpox and smallpox viruses, but the Acambis product is grown in cell culture rather than on the flanks of calves. The ACAM2000 vaccine is shown here.
