[1] KK Womens & Childrens Hosp, Dept Pediat, 100 Bukit Timah Rd, Singapore 229899, Singapore
[2] Duke NUS Med Sch, Singapore, Singapore
[3] London Sch Hyg & Trop Med, Dept Infect Dis Epidemiol, London, England
[4] Publ Hlth England, Modelling & Econ Unit, London, England
[5] Duke NUS Med Sch, Ctr Quantitat Med, Singapore, Singapore
[6] KK Womens & Childrens Hosp, Dept Pediat Subspecialties, Childrens Intens Care Unit, Singapore, Singapore
[7] Natl Univ Singapore, Yong Loo Lin Sch Med, Singapore, Singapore