Preventable diseasesTexas Cities More Susceptible to Measles Outbreaks

Published 23 August 2019

The growing number of children arriving at Texas schools unvaccinated makes the state increasingly vulnerable to measles outbreaks in cities large and small, according to a new study. The findings indicate that an additional 5 percent decrease in vaccination rates, which have been on a downward trend since 2003, would increase the size of a potential measles outbreak by up to 4,000 percent in some communities.

The growing number of children arriving at Texas schools unvaccinated makes the state increasingly vulnerable to measles outbreaks in cities large and small, according to a computer simulation created by the University of Pittsburgh Graduate School of Public Health

The findings, published today in the journal JAMA Network Open, indicate that an additional 5 percent decrease in vaccination rates, which have been on a downward trend since 2003, would increase the size of a potential measles outbreak by up to 4,000 percent in some communities. 

“At current vaccination rates, there’s a significant chance of an outbreak involving more than 400 people right now in some Texas cities,” said lead author David Sinclair, Ph.D., a postdoctoral researcher in Pitt’s Public Health Dynamics Laboratory. “We forecast that a continuous reduction in vaccination rates would exponentially increase possible outbreak sizes.”

Measles is a highly contagious virus that can cause severe complications, including pneumonia, brain swelling and deafness. Approximately 1 out of every 1,000 children infected with measles will die from respiratory and neurologic complications. Measles is so contagious that, if no one was immunized, one infected person is likely to infect 12 to 16 others; in comparison, one person infected with the flu is expected to infect only one to two people. The measles vaccine — which is often combined with the mumps and rubella vaccines and called the “MMR vaccine” — is highly effective, conveying 97 percent immunity after two doses.

Pittsburgh says that Sinclair and his team loaded real-world vaccination data for private schools and public school districts in Texas in the Framework for Reconstructing Epidemiological Dynamics (FRED) tool. FRED is an “agent-based” modeling system, which means it creates a synthetic population using U.S. Census data and then assigns the synthetic people to move about their communities from home to work or school as people do in the real world. This tool allows users to see, in silica, how a contagion