Most Australians are unconcerned about swine flu, a poll found Wednesday, as the number of related deaths hit 53 and cases raced past 21,000. The survey found almost 60 percent thought the virus would have little or no impact on their health, or were unsure about its effects. Doctors meanwhile renewed calls for those considered vulnerable to be vigilant about their health after a 22-year-old man with underlying health problems became the latest to die. 'We are now focusing our attention on those in the community who may be at risk of severe illness, and targeting people with underlying conditions for testing, treatment and care,' said Tarun Weeramanthri, Western Australia's chief medical officer. The poll of 620 people, published online by the Medical Journal of Australia, found 96 percent knew about swine flu but 78.5 percent believed they didn't have a great risk of catching it. 'Despite a rapid increase in the number of pandemic (H1N1) 2009 cases worldwide and the heightened saturation of information about the disease and its spread, few of our respondents believed they were at high to very high risk of contracting pandemic influenza,' the study said. Respondents believed face masks were as effective as anti-viral drugs in countering the disease and rated quarantine as the best way to stop it. Early reports that the virus had only mild effects had shaped people's views, which could hamper efforts to encourage better public hygiene, the study said. The latest government figures showed 21,109 confirmed cases, up more than 10 percent from a day earlier, with 422 hospital including 97 in intensive care. Swine flu has caused the deaths of 816 people around the world, with most of the victims in the Americas region, according to data published Monday by the World Health Organisation. 