Pneumococcal vaccines have been used in the United States for over a decade. A number of questions remain about which risk groups benefit most from the direct and indirect benefits of the vaccine, what would be the optimal vaccination strategy for adults, and whether the emergence of novel clones could undermine vaccine impact. In ongoing studies, we are working with the Emerging Infections Program at the Connecticut Department of Public Health to evaluate spatial variations in the direct and indirect effects of pneumococcal vaccination. In addition, I am working with Zitta Harboe at Statens Serum Institut in Copenhagen to develop models to improve the interpretation of pneumococcal disease surveillance data and vaccine impact. In collaboration with Joice Reis, we are working to understand the serotype epidemiology in different risk groups in a favela population in Salvador, Brazil. In the wet lab, we are developing novel experimental approaches to understand how capsule switching influences bacterial fitness, and we are evaluating how vaccination of children has influenced immune responses in the elderly.
PneumoVIPR: Pneumococcal Vaccine ImPact Research. We are leading an effort to estimate vaccine impact in resource poor settings and to develop new analysis and policy tools to understand complex patterns in pneumonia hospitalizations found in administrative databases. For this project, we are collaborating with Lone Simonsen at George Washington University/University of Copenhagen and the team at Sage Analytica (Rob Taylor, Roger Lustig, Cynthia Schuck-Paim, Gerardo Chowell). Read more about it here.
I previously studied and worked in the laboratory of Marc Lipsitch at Harvard School of Public Health and sought to understand how the microbiological characteristics of pneumococcal serotypes influence their prevalence among carriers and their tendency to cause disease. We identified an association between the primary biochemical structure of the capsules and the prevalence of the strains among healthy carriers before and after vaccine introduction. Additionally, we found that the prevalence of serotypes among carriers was directly related to the severity of disease caused by those serotypes and inversely associated with invasiveness (cases/carrier ratio). These results were used to estimate the potential impacts of serotype replacement on disease incidence following vaccination. We also reviewed the evidence for serotype replacement following pneumococcal vaccination.