California health officials yesterday announced the state's second H5N1 avian flu infection in a dairy farm worker who had no known connection to its first case, as federal health officials announced new steps to boost the supply of H5N1 vaccines, if needed.

Public health officials in California have confirmed two human cases of bird flu, or avian influenza, the state Department of Public Health said. Both cases are located in the Central Valley region, and both patients had contact with dairy cattle infected with H5N2 bird flu.

Sixteen human bird flu cases have been reported in the United States this year, including the two workers who tested positive in California. Fifteen of those cases were in farm workers at infected poultry or dairy farms.