Previous drugs to treat the disease have failed and were never approved: An effort from Centocor went down in 1992, and drugs from Chiron (nasdaq: CHIR - news - people ) and Synergen failed in 1994.
Chiron (nasdaq: CHIR - news - people ), one of only two drugmakers that supply America with flu shots, said British regulators suspended its license for the Liverpool, England, facility where it makes all of its flu shots.