London ? About half of Hong Kong’s health workers would refuse the swine flu vaccine, new research says, a trend that experts say would likely apply worldwide.

In a study that polled 2,255 Hong Kong health workers this year, researchers found even during the height of global swine flu panic in May, less than half were willing to get vaccinated.

Most said they would pass on the swine flu shot, which is not yet available, because they were afraid of side effects and doubted how safe and effective it would be.

Doctors and nurses are on the swine flu front lines — and if they become infected, they may not only spread the disease to patients but also their absence from work could cripple health systems.

The World Health Organization recommends countries vaccinate their health workers. Many Western countries including Britain, Spain, and the U.S. have said doctors and nurses will be among the first to get swine flu shots.