Published in the June issue of Health Affairs, the study used a detailed computer simulation of the Washington, D.C., metropolitan area and found limiting or delaying the vaccination of residents in poorer counties could raise the total number of influenza infections. Moreover, inequitable access to vaccinations increased the number of new infections during the peak of an epidemic in both poor and wealthier counties – even though the wealthier counties had received more timely and abundant vaccine access.
“When vaccines are in short supply, distributing them quickly and equitably among populations and localities can be a difficult challenge,” said the study’s lead author, Bruce Y. Lee, M.D., M.B.A., assistant professor of medicine, epidemiology and biomedical informatics at the University of Pittsburgh. “However, policymakers across the country, in poor and wealthy areas alike, have an incentive to ensure that poorer residents have equal access to vaccines.”
Dr. Lee is the Applied Modeling Project principal investigator for the Models of Infectious Disease Agent Study (MIDAS) National Center of Excellence, also at the University of Pittsburgh. He and his co-authors developed the flu vaccination model while working with the Department of Health and Human Services during the 2009 H1N1 pandemic. The team studied how the course of the pandemic might have been affected by vaccinating residents of various counties at different rates and times.
Computer simulation modeling suggested that equitable vaccination could reduce an epidemic’s severity because poorer counties tend to have high-density populations and more higher-risk people — such as children – per household, resulting in more interactions. This leads to increased transmission of influenza and greater risk for poorer influenza outcomes, the study said.
Even with the best intentions, inadequate infrastructure, geographical or socioeconomic barriers or cultural differences can lead to inequitable access to vaccines, Dr. Lee said. Research has shown that poorer people may have less access to medical care, including vaccination, than wealthier people.
The study was supported by the National Institute of General Medical Sciences Models of Infectious Disease Agent Study and the Vaccine Modeling Initiative, funded by the Bill & Melinda Gates Foundation. Co-authors include Shawn T. Brown, Ph.D., Rachel R. Bailey, Richard K. Zimmerman, M.D., Margaret Ann Potter, J.D., Sarah M. McGlone, John J. Grefenstette, Ph.D., Shanta M. Zimmer, M.D., and Sandra Crouse Quinn, Ph.D., all of the University of Pittsburgh; Donald S. Burke, M.D., dean of the University of Pittsburgh Graduate School of Public Health and head of the MIDAS center; Philip Cooley and William D. Wheaton, of RTI International; and Ronald Voorhees, of the Allegheny County Health Department.
The Modeling of Infectious Disease Agent Study (MIDAS) was initiated by the National Institute of General Medical Sciences to investigate novel computational and mathematical models of existing and emerging infectious diseases. In 2009, the University of Pittsburgh was designated a MIDAS National Center of Excellence, leading a collaborative network of scientists in the development and use of computational models that will prepare the nation to respond to outbreaks of infectious diseases, such as the H1N1 swine flu. The MIDAS research agenda includes the development of computational tools for the analysis of the dynamics of emergent diseases and for the predictive evaluation of the effectiveness of proposed intervention strategies.
The University of Pittsburgh Graduate School of Public Health (GSPH), founded in 1948 and now one of the top-ranked schools of public health in the United States, conducts research on public health and medical care that improves the lives of millions of people around the world. GSPH is a leader in devising new methods to prevent and treat cardiovascular diseases, HIV/AIDS, cancer and other important public health issues. For more information about GSPH, visit the school’s website at http://www.publichealth.pitt.edu.