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March 5, 2015

Simulation demonstrates impact of measles outbreaks

measlesTo bring facts and clarity to the public debate about immunization in light of recent measles outbreaks, the Graduate School of Public Health has unveiled a computer simulation that explores the impact of such outbreaks across the U.S. Users can see how an outbreak would play out if their city had high or low vaccination rates.

The simulation, which is accessible from mobile devices, is an adaptation of the popular Framework for Reconstructing Epidemiological Dynamics (FRED), a free resource created at Pitt. By visiting, people can select cities they’re interested in and watch short animations that play out an outbreak with either high or low vaccination coverage.

Examining the impact of high and low vaccination rates allows people to grasp the concept of herd immunity, explained Donald S. Burke, public health dean and UPMC-Jonas Salk Chair of Global Health. The Centers for Disease Control and Prevention estimates that when 95 percent of a community — or the “herd” — is vaccinated against measles, the 5 percent who can’t be vaccinated because they are too young or have compromised immune systems, as well as those whose immunity wore off or never took hold, should be protected because the virus can’t gain a foothold and spread. When vaccination rates dip too low, the herd isn’t protected and measles can sweep through a community.

Measles is a highly contagious virus. If someone with measles is in a room, nine out of 10 unvaccinated people in that room will contract the virus. For two hours after the infected person leaves, the room’s air will harbor the virus.

The measles, mumps, rubella (MMR) vaccine is recommended for children 12-15 months of age, with a booster usually given between 4-6 years of age. Older children and adults who missed the vaccine or aren’t sure if they received it can get immunized by their doctor or at a clinic.

Future iterations of FRED Measles will allow users to adjust vaccination rates and experiment with how closing schools could affect an outbreak.

“Teachers could use FRED to help their students get a hands-on look at how public health interventions impact an infectious disease outbreak,” said FRED creator John Grefenstette, faculty  member in health policy and management. “It’s also something that pediatricians could use to open a dialogue with parents who may not want to vaccinate their children.”

FRED was created at Pitt’s Models of Infectious Disease Agent Study Center of Excellence, which is supported by the National Institute of General Medical Sciences.