Efforts to combat bird flu will shift to prevention - rather than relying on the mass slaughter of poultry stocks - under a government plan to be unveiled today. The approach is expected to focus on the vaccination of chickens and improved safety measures on farms, including means to prevent contact with wild birds that could be carrying the bird flu virus. The measures, which will be announced today by Secretary for Health, Welfare and Food Yeoh Eng-kiong, come as Hong Kong is battling its fourth outbreak of bird flu. As in the past three outbreaks since 1997, thousands of chickens have been slaughtered on farms. Now officials are believed to be looking at a more comprehensive strategy aimed at tackling the factors that lead to an outbreak. However, Derek Gould, a retired principal assistant secretary for health and welfare, fears the government will not go far enough in its preventive approach. 'They have only developed a mechanism to contain the problem every time it breaks out. It is not preventive, to try to prevent the birds from getting infected with flu in the first place, not slaughter the birds after they got it,' he said. 'The impression I get is that they will tighten the monitoring so that we can catch the outbreak earlier, not prevent the outbreak through improvement of the farms, the health of the birds, the way they are stocked, handling in the markets and so on.' Legislator for the medical sector Lo Wing-lok said vaccination of all chickens as a routine measure should only be administered once data had been collected from a pilot programme that began in April last year. Chinese University professor of microbiology John Tam Siu-lun, who is a member of the government flu expert team, said biosecurity of farms - involving measures to keep poultry stocks safe from infection - must be up to international standards. 'Bird flu is now in wild birds and they could go anywhere,' Professor Tam said, adding birds in parks and gardens should be monitored. Early last month, waterfowl were found with the bird flu virus in Penfold Park at Sha Tin racecourse. Birds in Kowloon Park, and chickens in five wet markets and two farms have since been infected. About 28,500 chickens have been slaughtered or have died.