aDepartment of Social Medicine, University of Bristol, UKbKnowledge Translation Unit, University of Cape Town Lung Institute, University of Cape Town, South AfricacFree State Department of Health, Bloemfontein, South AfricadSchool of Medicine, Health Policy and Practice, University of East Anglia, Norwich, UKeInstitute of Social & Preventive Medicine (ISPM), University of Bern, SwitzerlandfDepartment of Medicine, University of Cape Town, South Africa.