Federal officials plan to double the stockpile of emergency bird flu vaccines as they identify more people infected with the disease. Three manufacturers were awarded $72 million to increase pandemic preparedness including against avian influenza, officials announced in a Friday morning briefing.

California is investigating a possible case of bird flu in a person who had contact with infected dairy cattle, the state's public health department said on Thursday.

Both patients were dairy workers whose illnesses were mild. Investigators are continuing to evaluate the contacts of a Missouri patient who had no exposure to animals.