As thousands of unvaccinated kids head back to school in Texas, several cities could be facing huge measles outbreaks, a new study suggests.
Vaccination rates in the Lone Star State have been on a downward trend since 2003 as more parents opt their children out for religious or personal reasons.
Texas is one of 17 states that allow exemptions for these reasons, and the findings serve a kind of case study of what could happen in any of these states.
Researchers ran a computer simulation and found that an additional decrease in vaccination rates of just five percent could more than double the size of a potential measles outbreak from 400 to 1,000 cases.
About 40 percent of these cases would occur in people who have a medical condition that prevents them from getting vaccinated.
It comes as new figures revealed this week that the current, historic measles outbreak is continuing to spread across the US, with 21 new cases confirmed, bringing the total to 1,203 across 30 states.
The team, from the University of Pittsburgh Graduate School of Public Health, says limiting vaccine exemptions may be the only way to prevent a large and deadly outbreak.
This simulation shows how a measles outbreak could spread in Austin, Texas, if vaccination rates drop by 10% and a single measles case is introduced
‘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 at the University of Pittsburgh’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 could lead to life-threatening complications including brain swelling and pneumonia.
Researchers say measles is so contagious that, if no one is vaccinated, one infected person could pass on the virus to as many as 16 people.
By comparison, someone with the flu would likely only infect one or two others.
Once common, measles is now relatively rare due to the MMR (measles, mumps, rubella) vaccine.
The Centers for Disease Control and Prevention (CDC) recommends children receive the first dose at 12 to 15 months old and the second dose at four to six years old.
The vaccine is about 97 percent effective. But those who are unvaccinated have a 90 percent chance of catching measles if they breathe the virus in, the CDC says.
The Texas Pediatric Society asked University of Pittsburgh researchers to conduct a computer simulation of the possibility of outbreaks in Texas communities with low vaccination rates.
Texas is one of 17 states that allows parent to opt their kids out of vaccinations for religious beliefs and personal/philosophical beliefs.
Such exemptions rose 28-fold in Texas, from 2,300 in 2013 to 64,000 in 2016.
‘Based on the huge numbers of non-medical exemptions allowed in Texas, the state is at a very high risk for a measles epidemic,’ Dr Peter Hotez, professor of pediatrics and dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, Texas, told DailyMail.com.
The state’s capital, Austin, is also currently the home of disgraced physician Andrew Wakefield, who authored a fraudulent research paper in 1998 linking the MMR vaccine to autism.
The team loaded vaccination data for both public and private school districts in Texas into the Framework for Reconstructing Epidemiological Dynamics (FRED) tool.
FRED creates a computer simulation of people moving about their communities – such as home, work and school – as they would in the real world and shows how a disease could spread.
Researchers introduced a single case of measles in various areas and ran the simulation in each city for 270 days, the length of a standard school year.
At current vaccination rates, the simulation showed, if a singles measles cases was introduces, an outbreak with more than 400 cases could occur in Austin and in the nearby city of Dallas-Fort Worth.
The team says this is because, in some schools, vaccination rates are below 92 percent – low enough for meals to easily spread.
A simulation was then run that showed a hypothetical decrease in vaccination rates.
If the vaccination rate drops just five percent, Austin, Dallas-Fort Worth and Houston would all potentially see measles outbreaks of between 500 and 1,000 people.
About 64 percent of these cases would occur in children whose parents had opted them out of immunizations.
But a rather high 36 percent would occur in those who are unable to be vaccinated, including the ill, very young and very old.
‘When someone refuses to be vaccinated, they are making a decision that doesn’t only impact them,’ said senior author Dr Mark Roberts, chair of Pitt Public Health’s Department of Health Policy and Management.
‘They are increasing the risk that people who are not immune, through no fault of their own, will get very sick and possibly die.’
Dr Hotez, who was not involved in the research, say he believes that not only will a measles epidemic eventually strike Texas, but that it will be larger than the researchers estimate.
‘This doesn’t even say anything about the 325,000 kids homeschooled in Texas,’ he said. ‘These studies confirm that…a big one is coming, because it almost certainly will.’