1. Institute of Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
2. Department of Microbiology and Immunology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
3. Department of Research, Kilimanjaro Clinical Research Institute, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
4. Department of Internal Medicine, Kilimanjaro Christian Medical University College, Moshi, Tanzania
5. Department of Health Management Systems, Kilimanjaro Christian Medical University College, Moshi, Tanzania
6. Department of Paediatrics and Child Health, Kilimanjaro Christian Medical University College, Moshi, Tanzania
7. Health Economics and Health Technology Assessment, Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK