[1] Univ Oxford, Clin Res Unit, Hosp Trop Dis, Ho Chi Minh City, Vietnam
[2] Hosp Trop Dis, Ho Chi Minh City, Vietnam
[3] Mahidol Univ, Fac Trop Med, Mahidol Oxford Trop Med Res Unit, Bangkok, Thailand
[4] Univ Oxford, Churchill Hosp, Ctr Clin Vaccinol & Trop Med, Oxford, England