The Hong Kong government shut down all poultry farms and markets and culled 80,000 chickens on Tuesday following the reemergence of bird flu, the South China Morning Post reported. Imports of mainland chickens have also been halted. The H5 avian influenza virus killed 200 chickens at a farm in the New Territories despite the government’s anti-bird flu control program. It was unclear whether the virus had mutated or the Dutch-made vaccine being used on local chickens had failed. The dead chickens included vaccinated as well as unvaccinated birds. It is the first outbreak on a farm since 2003, after which chickens were vaccinated. In June, poultry trading was temporarily suspended following the discovery of the virus in wet markets, which led to a ban on keeping chickens overnight in markets.