Swine flu vaccinations may begin in three weeks, earlier than previously anticipated, after the first U.S. tests found a single shot to be effective in eight to 10 days, U.S. health officials said.

The first shots may be available by the end of this month and administered to patients the first week of October, said Nancy Cox, director of the flu division at the U.S. Centers for Disease Control and Prevention in Atlanta. Health officials had previously planned for vaccinations to begin in mid-October, requiring two shots administered three weeks apart. ...