Soaring egg prices have consumers boiling, and on Wednesday, the United States Department of Agriculture blamed rising costs on the bird flu epidemic and said it will take new steps to quell the outbreak.

Dr. Carlson said with only conditional approval, there are still many steps to accomplish, and that could take a year or two before the vaccine is released in large quantities.

The US Department of Agriculture (USDA) Center for Veterinary Biologics (CVB) has issued a conditional license for an avian influenza vaccine, H5N2 subtype, killed virus. The vaccine, manufactured by Zoetis, is labeled for use in chickens.