I am a clinician and epidemiologist from the UK. I trained in clinical medicine at Oxford University and did specialty training in Infectious Diseases at hospitals in London, Newcastle and Oxford. I then trained in epidemiology at the London School of Hygiene & Tropical Medicine (LSHTM) and in 1993 I moved to the KEMRI-Wellcome Trust Research Programme in Kilifi, Kenya where I have worked ever since. My interests have ranged across the aetiology of pneumonia in adults and children, transmission of pneumococci in households, diagnosis of pneumococcal disease, pneumococcal seroepidemiology, new vaccine development, effectiveness of conjugate vaccines against Hib and pneumococcus and the use of carriage studies to evaluate vaccine interventions across Africa. I work on the Gates-funded “CHAMPS” study of causes of death in children in Ethiopia. Since 2013 I have also worked at LSHTM where I lead a research team that specialises in policy-relevant vaccine research in the UK and I teach on vaccine epidemiology. I have worked on vaccine policy in Kenya, UK and with WHO. During the COVID-19 pandemic I studied the seroepidemiology of SARS-CoV-2 in Kenya and the impact of the vaccine on mortality.