We develop study designs and statistical methods for evaluating effects of vaccines in populations that go beyond the direct protective effects in individuals. We have developed studies to evaluate the indirect effects in those who are not vaccinated as well as the combined effect of direct and indirect protection in those who do get vaccinated. We also develop methods to study the overall effects of vaccination programs. This research is applicable to both randomized and observational studies.
Methods for causal inference using potential outcomes often assume that an individual’s treatment does not affect the potential outcomes of others. However, in infectious diseases, interventions in one individual often do affect the outcomes of others. This research dealing with interference sets evaluating the different effects of vaccines in both randomized and observational studies in a formal framework. The research is also applicable to many other social and economic settings.
In this research we develop new methods for investigating immune correlates and surrogates of vaccine protection. Methods developed include combining information across studies and optimal combinations of immune markers as immune correlates.
Our research encompasses studies in influenza, pertussis, rotavirus, dengue, Zika, chikungunya, Ebola, tuberculosis among others. Our research is also part of the WHO Blueprint for Research and Development for emerging infectious diseases.