[1] Wyeth Vaccines Res, Pearl River, NY 10965 USA
[2] Novartis Pharmaceut, E Hanover, NJ USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Int Hlth, Ctr Amer Indian Hlth, Baltimore, MD 21205 USA
[4] Emory Univ, Rollins Sch Publ Hlth, Hubert Dept Global Hlth, Atlanta, GA 30322 USA
[5] Univ Witwatersrand, MRC, Resp & Meningeal Pathogens Res Unit, Johannesburg, South Africa