[1] Ctr Geog Med Res Coast, Kilifi, Kenya
[2] Univ Oxford, Ctr Clin Vaccinol & Trop Med, Oxford, England
[3] Univ Oxford, Dept Paediat, Oxford, England
[4] John Radcliffe Hosp, Hlth Protect Agcy Haemophilus Reference Unit, Oxford OX3 9DU, England
[5] Univ Liverpool, Dept Microbiol, Liverpool L69 3BX, Merseyside, England
[6] Univ London Imperial Coll Sci Technol & Med, Dept Paediat, London SW7 2AZ, England
[7] Univ London Imperial Coll Sci Technol & Med, Wellcome Trust Ctr Clin Trop Med, London SW7 2AZ, England