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 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 Dr. David Sinclair, 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.”
Dr. 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. At current rates, the simulation estimates that measles outbreaks of more than 400 cases could occur in Austin and Dallas-Fort Worth. This is partly due to a minority of schools where vaccination rates are less than 92 percent — low enough for measles to sustain transmission.
If the vaccination rate drops 5 percent in only the schools with populations that currently are undervaccinated, the size of potential measles outbreaks climbs exponentially in every metropolitan area, with Dallas-Fort Worth, Austin and Houston all susceptible to outbreaks of 500 to 1,000 people.Friday Letter Submission, Publish on September 06