The government is being urged not to rush to switch vaccines, as the H5N2 vaccine used to inoculate poultry at local farms has been shown to have prevented bird flu for the past 10 years in high-risk areas such as Mexico and Italy.
On Wednesday, Secretary for Food and Health York Chow Yat-ngok said University of Hong Kong test results on the usefulness of the Dutch vaccine on virus samples taken at four wet markets in June were 'not conclusive'.
Hong Kong has been using a H5N2 vaccine made by animal health care company InterVet from the Netherlands since the government started a vaccination programme for local farms in 2003.
InterVet's vaccine appeared to be effective until the H5 virus killed 200 chickens at a farm in Yuen Long on Monday and early Tuesday.
Animal virologist Frederick Leung Chi-ching of the University of Hong Kong said there was 'no proof' that the vaccine programme was not working. 'If anything, I would in fact argue that the vaccine programme is working fine,' he said.
He said animal experts had been asking the government since 1999 to add the vaccination programme to its bird flu control plan.
'The last five years' record of using vaccine is the proof of that. How one uses the vaccine is also very important as to the effectiveness of the vaccination programme,' he said.