[1] Univ Washington, Dept Epidemiol, 325 Ninth Ave,HMC 359931, Seattle, WA 98195 USA
[2] Univ Washington, Dept Biostat, Seattle, WA USA
[3] Univ Washington, Dept Med, Seattle, WA USA
[4] Statens Serum Inst, Copenhagen, Denmark
[5] Fred Hutchinson Canc Res Ctr, Seattle, WA USA
[6] Univ Washington, Dept Microbiol, Seattle, WA USA
[7] Univ Washington, Dept Global Hlth, Seattle, WA USA