[1] Int Primary Care Resp Grp, Edinburgh, Midlothian, Scotland
[2] Univ Edinburgh, Usher Inst, Edinburgh, Midlothian, Scotland
[3] Queen Mary Univ London, Inst Populat Hlth Sci, London, England
[4] UCL, Div Infect & Immun, London, England
[5] Univ Birmingham, Inst Appl Hlth Res, Birmingham, W Midlands, England
[6] Univ Glasgow, MRC CSO Social & Publ Hlth Sci Unit, Glasgow, Lanark, Scotland
[7] Univ Crete, Dept Social Med, Iraklion, Greece
[8] Univ Liverpool Liverpool Sch Trop Med, Dept Int Publ Hlth, Liverpool, Merseyside, England