More than half of healthcare workers surveyed in Hong Kong said they would refuse to be vaccinated against swine flu, according to a study released Wednesday. Fear of side effects and doubts as to efficacy were the two main reasons cited, said the study, published online by the British Medical Journal (BMJ). The Hong Kong survey echoes a recent sounding of 1,500 nurses in Britain, 30 percent of whom also said they would not allow themselves to be jabbed. Vaccinating health workers to protect essential health infrastructure is the cornerstone of virtually all international and national plans for coping with the swine flu virus. If doctors and nurses are sick as the pandemic peaks, it could wreak havoc on health care systems, experts warn. On Tuesday the European Union, following guidelines laid out by the World Health Organisation (WHO), said health workers should be vaccinated first, along with pregnant women and persons with underlying chronic conditions. US health authorities have outlined similar priorities. The reluctance of Hong Kong health professionals to be vaccinated is surprising, the authors say. The territory was hit especially hard by the SARS epidemic in 2002 and 2003, and the survey was conducted just after the WHO escalated its alert for the current pandemic to level five, just one notch shy of a full-blown pandemic. A team of researchers led by Paul Chan from the Chinese University of Hong Kong surveyed over 8,500 doctors, nurses, and other health professionals working at 31 hospital departments in Hong Kong. Participants were questioned first in early 2009, when the WHO influenza pandemic alert was at level 3, and again in May, when level had just be raised to 5. Results were virtually the same both times, with only 47 and 48 percent saying they would get vaccinated. The 'yes' cohort tended to be younger, had received the seasonal flu vaccine last season, and feared they were more likely to get swine flu. 'This study provides important information on barriers to vaccination,' the authors conclude. 'Campaigns to promote vaccination should consider addressing the knowledge gap of staff and the specific target groups for intervention.' In a commentary, also in the BMJ, Rachel Jordan from the University of Birmingham and Andrew Hayward from the UCL Centre for Infectious Disease Epidemiology in London point out that vaccination for healthcare workers is important for their own protection, as well as the wellbeing of patients. 