[1] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Int Hlth, Baltimore, MD 21205 USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Behav & Soc, Baltimore, MD 21205 USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Inst Vaccine Safety, Baltimore, MD 21205 USA
[4] Kaiser Permanente Colorado, Inst Hlth Res, Denver, CO USA
[5] Colorado Sch Publ Hlth, Dept Epidemiol, Aurora, CO USA
[6] Emory Univ, Rollins Sch Publ Hlth, Atlanta, GA 30322 USA