More Illinois parents are opting out of some school-required vaccinations for their kids, according to a new study by the Associated Press.

The study says the rate of vaccine exemption is 5.3 percent in Illinois, making it one of eight states where more than five percent of public school kindergartners do not get all the vaccinations that are required for attendance. Alaska had the highest rate, at nine percent.

Dr. Kenneth Soyemi works in the infectious disease department at the Illinois Department of Public Health. He said parents seek exemptions for some vaccines for medical, religious and, in states that allow it, philosophical reasons. Soyemi said kids who don’t get vaccinated could make diseases like measles and whooping cough harder to contain.

“Presuming children are not vaccinated in the school, if measles comes into the school, it’s going to spread like wild fire,” said Soyemi.

The survey also found more than half of all states have seen at least a slight rise in vaccine exemptions in last five years. Illinois is one of 10 states where the rate of vaccine exception increased more than 1.5 percentage points.