My research aims to strengthen the evidence for vaccine decision-making in low- and middle-income countries (LMICs). My work is interdisciplinary, integrating disease modelling, health economics, epidemiology, and health technology assessment. I have developed several analytical models to assess the costs and consequences of various vaccines, including those for rotavirus, human papillomavirus (HPV), and respiratory syncytial virus (RSV). The models provide a framework for stakeholder engagement, capacity strengthening, and national ownership of results, and have been used to support national vaccine committee decision-making in over 40 countries. My research has also informed global WHO guidelines e.g. the policy to relax rotavirus vaccine age restrictions in high mortality settings, and the roadmap for prioritising the use of COVID-19 vaccines. My research has provided insights into: (i) the substantial number of people at increased risk of severe COVID-19 disease due to chronic conditions (Clark et al, Lancet Global Health 2020); (ii) the favourable benefit-risk profile of rotavirus vaccines (Clark et al, Lancet Global Health 2019); (iii) variations in the efficacy and duration of protection of live oral rotavirus vaccines (Clark et al, Lancet Infectious Diseases 2019); and, (iv) the substantial delays in the administration of children’s vaccines in LMICs (Clark and Sanderson, Lancet 2009).