[1] South African Med Res Council, Environm & Hlth Res Unit, ZA-2028 Johannesburg, South Africa
[2] Univ Witwatersrand, Fac Hlth Sci, Sch Publ Hlth, ZA-2193 Johannesburg, South Africa
[3] Univ Johannesburg, Fac Hlth Sci, Environm Hlth Dept, ZA-2028 Johannesburg, South Africa
[4] Natl Inst Communicable Dis, Ctr Resp Dis & Meningitis, ZA-2193 Johannesburg, South Africa
[5] North West Univ, Sch Geo & Spatial Sci, Unit Environm Sci & Management, ZA-2520 Potchefstroom, South Africa
[6] Univ Witwatersrand, Perinatal HIV Res Unit PHRU, ZA-1864 Johannesburg, South Africa
[7] Univ Witwatersrand, MRC Wits Rural Publ Hlth & Hlth Transit Res Unit, Fac Hlth Sci, Sch Publ Hlth, ZA-2193 Johannesburg, South Africa
[8] US Ctr Dis Control & Prevent Atlanta, Influenza Div, Natl Ctr Immunizat & Resp Dis, Atlanta, GA 30329 USA
[9] Ctr Dis Control & Prevent South Africa, Influenza Program, ZA-0181 Pretoria, South Africa
[10] MassGenics, Duluth, GA 30096 USA