[1] Santa Clara Valley Med Ctr, Dept Med, Div Infect Dis, San Jose, CA 95128 USA
[2] Univ Rochester, Sch Med & Dent, Sch Med, Rochester, NY USA
[3] Stanford Univ, Sch Med, Stanford, CA 94305 USA
[4] Univ Calif Irvine, Orange, CA 92668 USA
[5] RAND Corp, Los Angeles, CA USA