NOTE: This article has been updated to reflect the announcement Friday that Baylor University researchers had inadvertently inflated their Pennsylvania data.
Pennsylvania is one of a dozen states nationwide that have seen increases in parents choosing to not vaccinate their children against measles and other infectious diseases, according to a new study published this week..
The researchers fear growth in the anti-vaccine movement — parents who believe, contrary to scientific evidence, that vaccines are more dangerous than the diseases they protect against — could potentially present a public health threat.
“This is a wake-up call,” said Peter Hotez, a lead researcher and dean of the National School of Tropical Medicine at Baylor College of Medicine in Texas. “We really need to do a deeper dive now to figure out what’s going on in the hot-spot areas and what’s causing parents to not vaccinate their kids.”
The study by researchers from Baylor and the Texas Children’s Hospital Center for Vaccine Development was published Tuesday in the journal PLOS Medicine. It analyzed the growth in non-medical exemptions – opt-outs on the basis of religious, philosophical, or personal beliefs. They found that since 2009, 12 of the 18 states that allow such exemptions have seen increases in children not being vaccinated.
Eight Idaho counties were among the 10 counties with the nation’s highest exemption rates for kindergarten students in the 2016-17 school year, ranging from a high of nearly 27 percent to almost 15 percent. The two other highest counties were in Wisconsin and Utah.
By comparison, Pennsylvania’s highest non-medical exemption rates for kindergartners in 2015-16 were nearly 4.6 percent in Potter County, 4.4 percent in Armstrong County, and nearly 4 percent in Beaver County. Locally, Bucks County had the highest opt-out rates at 2.3 percent, Philadelphia had the lowest at less than 1 percent.
In Pennsylvania, children can be exempted from vaccines based on religious grounds, but their parents or guardians are not required to furnish proof of a religious belief.
“The department believes its data shows that the number of students obtaining exemptions is nominal and typically is less than 2 percent for each type of exemption available in Pennsylvania,” namely religious or medical, said Nate Wardle, a state Health Department spokesman.
In January, a national Blue Cross Blue Shield study found that the early childhood vaccination rate for commercially insured households in the Philadelphia area had improved from 2010 to 2016.
According to the Blue Cross Blue Shield claims data, over 85 percent of all Philadelphia-area children had received the federally recommended seven-vaccine series. Nationally, 73.5 percent of the insurer’s young members were up-to-date in their immunizations.
Interestingly, the Blue Cross study did find a national increase in the rate of parents refusing to get their children vaccinated – from 2.5 percent for children born in 2010 to 4.2 percent for youngsters born in 2013. The Philadelphia rate of parental refusal over the six-year study was 3.8 percent, higher than the national rate of 3.3 percent.
Hotez said that while it is true vaccination rates nationally have not changed dramatically, there is still cause for concern about public health, particularly with measles, a highly contagious and potentially fatal disease. In recent years, measles outbreaks in Minnesota and California have resulted in hospitalizations of young children. Those at most increased risk, he said, are the non-vaccinated children’s siblings under age 1 who are too young to be immunized.
“Once you start getting vaccination rates below 95 percent, then you start getting concerned,” Hotez said. “If it goes below 90 and 80 percent, then you get really concerned.”
Wardle said Pennsylvania has seen isolated measles outbreaks in the last few years, “but nothing widespread.”