Thought bird flu was gone? Recent human deaths in Asia and Egypt are a reminder that the deadly H5N1 virus is still alive and dangerous. Vietnam is also grappling with a new strain that has outsmarted vaccines long used to help protect its poultry flocks.

Ten people have died in Cambodia, Indonesia, Egypt, China and Vietnam since December during the prime-time flu season when the virus typically flares in poultry. In Vietnam, authorities can no longer rely on the latest poultry vaccine in the north and central regions where new virus strains have been detected.

boston.co