A team of infectious disease computer modelers at the University of Pittsburgh have launched a free, mobile-friendly tool that allows users simulate measles outbreaks in cities across the country, to help us better understand how measles spread.
The tool is part of the Pitt team's Framework for Reconstructing Epidemiological Dynamics (FRED) that it previously developed to simulate flu epidemics. FRED is based on anonymized US census data that captures demographic and geographic distributions of different communities. It also incorporates details about the simulated disease, such as how contagious it is.
In the simulations shown, an outbreak begins with a single case of measles. On the left screen, colored dots representing measles cases quickly cover the area. On the right screen, only a few dots cluster around the initial case. The difference is the vaccination rate: 80 percent (left) versus 95 percent (right) of school-aged children.
"The visualizations show the importance of a high vaccination rate in providing protection for the entire community," says Ravi Ravichandran, PhD, an expert on modeling the spread of infectious diseases.
This concept is called community or "herd" immunity: Immunizing a large segment of a population against a contagious disease reduces the ability of that disease to spread. Last October, the Centers for Disease Control and Prevention published details about vaccination coverage among kindergartners for vaccine-preventable diseases. The coverage for measles varies by state, ranging from 81 to 99 percent.
Planned versions of FRED Measles will allow users to change vaccination rates and also to explore the effects of school closures on disease spread.
Donald S. Burke, MD, dean of the Graduate School of Public Health, director of the Center for Vaccine Research, associate vice chancellor for Global Health, University of Pittsburgh, (and the first occupant of the UPMC-Jonas Salk Chair in Global Health)--who led the development of FRED--says he hopes this "fact-based tool will help people understand the importance of immunization."
[Source: NIH, National Institute of General Medical Sciences (NIGMS)]