[1] Columbia Univ, Mailman Sch Publ Hlth, Ctr Infect & Immun, New York, NY 10032 USA
[2] Natl Inst Communicable Dis, Div Natl Hlth Lab Serv, ZA-2131 Johannesburg, South Africa
[3] Univ Witwatersrand, Dept Sci & Technol, Natl Res Fdn Vaccine Preventable Dis, Johannesburg 2050, South Africa
[4] Child Survival Theme, Med Res Council Unit, Banjul, Gambia
[5] New York City Dept Hlth & Mental Hyg, Gotham Ctr, New York, NY 11101 USA