The policy of free healthcare for children under the age of 6 years in Vietnam: Assessment of the uptake for children hospitalised with acute diarrhoea in Ho Chi Minh City by Shieh, M, Thompson, C, Phan Vu Tra, M, Thi Thuy Linh, V, Tediosi, F, Merson, L, Farrar, J, Manh Tuan, H, Lu Viet, H, Thi Ngoc Tuyet, P, Baker, S