Vaccines could be a key means of suppressing bird flu and avoiding the slaughter of millions of chickens, which is blamed for egg prices averaging nearly $6 a dozen. But the move has been delayed in part because of concerns it could jeopardize chicken exports worth billions of dollars a year.

The U.S. Department of Agriculture has announced plans to spend $100 million to study bird flu vaccines to fight the disease in concert with meat chicken, egg and turkey groups.

The United States is facing a dilemma over poultry vaccination as egg prices soar. While vaccinating against bird flu could prevent mass culling and stabilise supply, concerns over trade restrictions and virus monitoring have slowed progress.

N EW YORK — Egg prices again reached a record high in February, as the bird flu continues to run rampant and Easter and Passover approach. The latest monthly Consumer Price Index showed a dozen Grade A eggs cost an average of $5.90 in U.S. cities in February, up 10.4% from a year ago. That eclipsed January's record-high price of $4.95.