Stephen researches Emerging Risks for the Swiss Re Institute focusing on Life & Health issues. He is a mathematical demographer. His work in infectious diseases began when he joined Metropolitan Life in South Africa at a time when HIV-related mortality was growing rapidly. Modelling was essential to understanding the risk and he developed what ultimately became the Actuarial Society models, based on some earlier model concepts. They were sufficiently robust for use in insurance pricing but were then further developed to give insights into social questions such as HIV-related orphanhood, and the costs of an HIV treatment program, for the country.
In late 2005 Swiss Re approached him about their need for a pandemic flu model, and he joined Swiss Re in 2006. The model was built, described and after a protracted approval process by the Swiss regulator, adopted as Swiss Re's mortality shock model. When the Catalyst Unit was set up, he rejoined Swiss Re, moving to Underwriting and then Swiss Re Institute. Recent projects include the Bio-innovation Risk Reduction Initiative, work with Public Sector Initiatives on a World Bank feasibility study assessing the use of data and models to target funds & eliminate the risk of famine, behavior modification to minimize exposure to ambient air pollution, and now of course, the fast moving pandemic of coronavirus.