Washington ? Combination vaccines that could point the way to a more efficient and cost-effective means of battling bird flu have been created by separate teams of researchers.

Scientists in the United States and Germany reported on methods of combining vaccines for flu and Newcastle disease.

The highly pathogenic H5N1 avian flu has raised concerns, with millions of birds killed in Asia and elsewhere. More than 120 people have died.

Scientists worry that the virus will evolve into a form that could cause an epidemic among people.

The Agriculture Department reports it has a stockpile of bird flu vaccine for poultry, and vaccines for people are in production.

Newcastle disease affects poultry and is currently avoided by routine vaccination. The teams of researchers were able to engineer combination vaccines to protect against bird flu and Newcastle disease.