The British government delivered a major blow to the U.S. health prospects this winter when it shuttered Chiron's (CHIR) flu vaccine shipments, leaving a significant shortage that sent U.S. health officials scrambling. The only other major supplier, Aventis (AVE), a unit of Sanofi-Aventis (SNY), appears able cover only another 10% from its inventory, and there are doubts about that. Medimmune (MEDI) can produce only 2 million flu vaccine doses out of about 100 million needed. Flu season begins in November. Flu shots are usually given in October. It takes six months to bring a production cycle up to par. Some...