[1] Univ North Carolina Chapel Hill, UNC Gillings Sch Global Publ Hlth, Dept Epidemiol, Chapel Hill, NC 27599 USA
[2] Univ North Carolina Chapel Hill, Inst Global Hlth & Infect Dis, Sch Med, Chapel Hill, NC 27599 USA
[3] Univ North Carolina Chapel Hill, UNC Gillings Sch Publ Hlth, Dept Biostat, Chapel Hill, NC USA
[4] Univ Penn, Wharton Sch, Dept Stat & Data Sci, Philadelphia, PA USA