Scientists at Chinese University are revisiting some of the hospitals that battled Sars to find out how 'super-spreaders' infected large numbers of people in the 2003 outbreak. The study is being led by Joseph Sung Jao-yiu, director of the university's Centre for Emerging Infectious Diseases, who said researchers wanted to learn more about how to protect hospitals from similar outbreaks. Professor Sung, who led the 'Sars dirty team' that helped to control the outbreak at Prince of Wales Hospital, and his team are also surveying hospitals in Guangdong and Canada. 'We are going to Canada to study how hospitals were working during the outbreak and compare those outbreaks and see whether there are any factors which precipitated the super-spreading events,' he said. 'We are doing studies on how hospital super-spreading events can occur.' Sars first became internationally known when it broke out at Ward 8B at Prince of Wales Hospital on March 10, 2003. The patient who spread the infection was identified days later as a Chek Lap Kok airport worker. He was admitted to the ward on March 5 with a fever, but no connection was made to atypical pneumonia, which Sars was then called. He had been treated with a nebuliser, which sprayed viral-laden mist onto nearby patients, hospital staff and medical students. The use of a nebuliser has been established as the super-spreading event in several scientific papers and by the Sars expert committee. Professor Sung said he agreed with various experts that Sars had largely been contained. 'I would not be so confident to say that it will not come back because the animal reservoir is still there,' he said. 'But given that we have tight surveillance in many countries, I do not think a large-scale outbreak is likely.'