HK chickens culled in bid to halt bird flu

HONG KONG: Health workers began culling thousands of chickens at a market here yesterday, a day after authorities raised the bird flu alert level to "serious" following an outbreak at a farm.

The outbreak near the border with the mainland was the region's first in five years and came despite mass vaccination of birds, prompting concerns the virus might have mutated.

Ho Pak-leung, a microbiologist at the University of Hong Kong, said: "The vaccine's effectiveness today will not be the same as it was five years ago."