Bryan T. Grenfell

Bryan T. Grenfell proposed “phylodynamics,” a methodology that predicts infectious disease dynamics of RNA viruses by considering viral evolution, and thus contributed to the development of the research field that integrates immune dynamics, epidemiology, and evolutionary biology. By virtue of these achievements, he has been instrumental in understanding infection mechanisms and proposing effective infectious disease control policies.

Pathogens threaten the lives of many organisms, including human beings. Vertebrates have developed adaptive immunity that prevents reinfection with the same pathogen. However, evolution by mutation enables pathogens to evade host immune responses. In 2004, Bryan T. Grenfell proposed “phylodynamics,” a new methodology that predicts the epidemic dynamics of RNA viruses by considering viral evolution and contributed to the development of the research field that integrates immune dynamics, epidemiology, and evolutionary biology.

In the phylodynamics framework, pandemic frequency and periodicity are analyzed by traditional epidemic models incorporating both dynamics of hosts’ immunity acquisition and pathogens’ immune evasion. Phylodynamics explains the major differences in the epidemic dynamics and evolutionary patterns of RNA viruses by the differences in the viral evolutionary potential to evade the host’s immunity by mutation (antigenic drift).

Grenfell began his research on wildlife population dynamics and later moved on to study zoonotic diseases. He successfully constructed a comprehensive framework that analyzes and predicts various infectious disease dynamics. He first developed a method for estimating parameters related to infectious processes in non-linear dynamical models that may exhibit chaotic behavior using long-term spatiotemporal data including uncertainty, which allows reliable predictions. Subsequently, he invented a method to detect spatial spread of infection in traveling waves. He also analyzed the spatiotemporal dynamics of measles using 50-year long-term statistics of the number of patients with measles. By applying these methodologies to various infectious disease data, such as those of influenza, foot-and-mouth disease, and dengue, Grenfell promoted the understanding of infection mechanisms and proposed effective control policies for various infectious diseases.

After the emergence of COVID-19, Grenfell investigated the evolutionary and epidemiological dynamics of the virus by considering the effectiveness of vaccination and the decline in its effects and discussed the vaccination policy to reduce the evolution of novel mutants. A series of these works are products of his research on wildlife population dynamics, and they are important for overcoming the COVID-19 pandemic, which is a major humanitarian crisis. This demonstrates the importance of basic research in ecology and evolutionary biology.

For these reasons, the Inamori Foundation is pleased to present the 2022 Kyoto Prize in Basic Sciences to Bryan T. Grenfell.