With bird flu threat expected to linger, USDA begins working on potential vaccine

The U.S. Department of Agriculture is working on a potential vaccine in response to the current outbreak of a deadly strain of bird flu that has cost turkey and chicken producers more than 6.7 million birds since early March.

A pure "seed strain" would target the H5N2 virus and some other highly pathogenic viruses in the H5 family that have been detected in other parts of North America. If the USDA decides the vaccine is necessary, it will provide the seed strain to private drug manufacturers.

Officials and poultry producers would also have to decide which birds will get the vaccine, look at how it might affect exports and gauge whether it'd be effective.

Experts say it isn't clear how much a vaccine would add to the cost of producing birds.