My research aims to improve understanding of the epidemiological factors and population processes that shape the spread of infectious diseases in human and animal populations. a key practical approach is the analysis and optimization of intervention strategies aimed at reducing the transmission or burden of disease. much of my work is applied, informing disease control policy making by public and global health institutions.
with recent advances in data availability (both epidemiological and molecular) and affordable high-performance computing, mathematical models of infectious disease spread now offer the potential to provide predictive and quantitative analyzes of alternative control strategies and treatment of diseases, as well as qualitative analysis. information about the complex non-linear processes that shape the replication and evolution of pathogens. therefore, an important aspect of my research program is to develop the statistical and mathematical tools necessary for these increasingly sophisticated models to be rigorously tested and validated with epidemiological, molecular, and experimental data. The breadth of my research interests reflects my belief that comparative analyzes of different host-pathogen systems can provide valuable insight into population processes common to many infectious diseases, while also highlighting how key differences in disease biology , the route of transmission or the structure of the host population determine differences in infection patterns.
a major research interest throughout my career has been the development of mathematical models of the geographic spread of emerging pathogens, such as bse/vcjd, foot-and-mouth disease, sars and mers, pandemic influenza, ebola, and zika, to examine containment and mitigation strategies. Much of this work has been done in collaboration with colleagues in my department and outside institutions, particularly public health partners such as the World Health Organization [WHO], the US Centers for Disease Control and Prevention, and Public Health. from England. these associations have been vital in facilitating the results of my work being used to inform policy. Building on our previous work, my colleagues and I founded the MRC Center for Global Analysis of Infectious Diseases (formerly known as the MRC Center for Outbreak Analysis and Modeling) in 2008 to consolidate and enhance our work on emerging infections and their translation to public health policy. doing. In 2019, the Abdul Latif Jameel Institute for Disease Analysis and Emergencies (J-IDEA) was launched to further bring together global health researchers at the School of Public Health and leverage Imperial’s expertise in data analysis, epidemiology and economy.
A second major current personal research interest is the epidemiology and control of major mosquito-borne diseases, particularly malaria (in collaboration with Azra Ghani) and ‘flavivirus’, a family of viruses that includes the dengue, yellow fever and zika. My group’s work on these viruses includes assessing the burden of disease, understanding how the intensity of transmission varies geographically and seasonally, and modeling the optimal use of current and novel interventions.
use of wolbachia as a new vector control measure
A strand of my recent work has examined the potential public health benefits of wolbachia, a new biological control to reduce the ability of Aedes aegypti mosquitoes to transmit dengue. In collaboration with Christl Donnelly and the Wolbachia End Dengue Initiative, we have estimated the potential impact of Wolbachia on dengue transmission and are now studying the spatial spread of Wolbachia after initial release. this work informs the design of the first large-scale trials of wolbachia and measures its impact on dengue transmission. The first trials of this type are likely to begin in Colombia and Indonesia, with studies in Vietnam and Brazil beginning shortly thereafter.
potential impact of the use of the dengue vaccine
recently published in science, my research on the sanofi vaccine (in collaboration with colleagues at the university of florida and johns hopkins university) examined the benefits and risks associated with large-scale immunization programs using this vaccine. our analysis showed that the complex efficacy trends observed in clinical trials of the vaccine were consistent with the hypothesis that the vaccine acted similarly to a silent (i.e., non-symptomatic) natural infection, by stimulating people’s immune systems who have never had dengue (and thus potentially increase their risk of experiencing severe dengue infection in the future), but boosting the immunity of those who experienced dengue before being vaccinated (thereby drastically reducing their risk of experiencing a severe dengue disease in the future). our analysis showed that this means that the use of the vaccine can substantially reduce the number of dengue cases when used in high transmission intensity settings, but could increase the number of hospitalized dengue cases if used in low intensity settings transmission where the majority of vaccinated children have not yet been infected with dengue my work informed and supports the recommendations of the who scientific advisory expert group [sage] on immunization on the use of this vaccine.
In ongoing work, my colleagues and I are analyzing historical dengue serology and surveillance data to generate global maps indicating where use of the vaccine will provide public health benefits and where it may pose risks. Examples of the former include high transmission intensity countries such as the Philippines, while examples of the latter include low transmission areas such as Singapore and Queensland, Australia. however, many countries, such as brazil, colombia, and malaysia, have substantial variation in transmission intensity from district to district, meaning that decisions about vaccination implementation will need to be made at the subnational level. For example, the use of the vaccine could reduce the number of dengue cases by a quarter in northern Brazil, but may have negative results if used in areas of lower transmission intensity in southern Brazil. this highlights the importance of careful and clear communication with policy makers and the public about the potential impact of using this vaccine in different settings.