Hong Kong has asked Mainland authorities to do a joint study to see if the H5N1 vaccine is more effective than the H5N2 vaccine currently used in the city, Secretary for Food & Health Dr York Chow says. It will also work with the University of Hong Kong to see if it is better way of vaccination.

Speaking to reporters today Dr Chow said the Government will inspect the Yuen Long farm affected recently by a bird flu outbreak to see whether it lacks biosecurity, and will also study if there is a change of immunity of its chickens.

"We have been using the H5N2 vaccines manufactured in the Netherlands. Over the last few years it has been proven to be effective, but we also think because of the change of the virus, we might have to look for a more appropriate vaccine," he said.

"The Mainland has introduced an H5N1 vaccine in the last few years. They have also modified it every now and then. So we have explored this option to look at whether we should change to the H5N1 vaccine too. But it is too pre-mature to decide on that."