Fig. 3

Distribution of research priorities by research type (n = 2145). Extracted from WHO publications published 2002–2017. The five research type categories were adapted and defined here as: 1. Problem: research to measure the size of the health problem through epidemiology, estimating the burden of disease and other forms of data collection. 2. Cause: research to understand the causal agents, risk factors and determinants of the health issue. May include, for example, study of infection cycle, vectors, role of socioeconomic factors, environment, diet and the interaction of multiple factors. 3. Solution: research to develop new interventions. Includes therapeutics, devices and procedures but also includes policy interventions, public health campaigns, etc. 4. Implementation: research to translate new interventions into policy and practice and understanding the barriers to delivering known interventions. 5. Evaluation: research to monitor and evaluate the effectiveness or health impact of an intervention or programme