[1] Stellenbosch Univ, Polit Sci, Stellenbosch, South Africa
[2] Univ Liverpool Liverpool Sch Trop Med, Clin Sci, Liverpool L3 5QA, England
[3] Univ Lagos, Coll Med, Dept Med, Lagos, Nigeria
[4] Lagos Univ Teaching Hosp, Dept Med, Surulere, Nigeria
[5] Royal Devon & Exeter Hosp, Dept Respirol, Exeter, England
[6] Imperial Coll London, London, England
[7] Univ Hosp Morecambe Bay NHS Trust, Kendal, England
[8] Tygerberg Acad Hosp, Dept Pulmonol, Cape Town, South Africa
[9] Stellenbosch Univ, Fac Med & Hlth Sci, Dept Pulmonol, Cape Town, South Africa
[10] Univ Sheffield, Acad Unit Primary Care, Sheffield, England
[11] Univ Cambridge, Dept Med, Cambridge, England
[12] Univ KwaZulu Natal, Coll Hlth Sci, Dept Med, Durban, South Africa
[13] Liverpool Univ Hosp NHS Fdn Trust, Liverpool, England