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Koh TH, Tan TT, Khoo CT, Ng SY, Tan TY, Hsu LY, Ooi EE, Van Der Reijden TJ, Dijkshoorn L.Koh TH, et al. Among authors: hsu ly.Epidemiol Infect. 2012 Mar;140(3):535-8. doi: 10.1017/S0950268811001129. Epub 2011 Jun 21.Epidemiol Infect. 2012.PMID: 21733253