Study design
This parallel, single-blind, randomised controlled trial was done in three districts in Ho Chi Minh City. Study clinics were established in three commune health centres, with participants recruited from those and surrounding communes. The protocol was approved by the institutional review board at the Pasteur Institute of Ho Chi Minh City. Ethical approval was obtained from the Royal Children's Hospital Melbourne human research ethics committee and the Viet Nam Ministry of Health ethics committee. The protocol has been published previously.