[1] Kings Coll London, Ctr Clin Infect & Diagnost Res, London WC2R 2LS, England
[2] Guys & St Thomas NHS Fdn Trust, London, England
[3] Aquarius Populat Hlth Ltd, London, England
[4] Univ Bristol, Sch Social & Community Med, Bristol, Avon, England
[5] Johns Hopkins Sch Publ Hlth, Dept Int Hlth, Baltimore, MD USA
[6] Guys & St Thomas NHS Fdn Trust, Evelina London Childrens Hosp, Dept Paediat Infect Dis, London, England