Another day, another study that underscores the societal benefits of vaccines and the consequences we’d face without them.
In a study published earlier this week in JAMA Pediatrics, researchers took on the issue of vaccine hesitancy by estimating the disease burden and economic costs associated with declines in the measles-mumps-rubella (MMR) vaccination rate. They noted that while overall childhood vaccine rates remain high in the U.S., there are areas where nonmedical exemption policies are materializing into declining immunization coverage.
For example, this 2016 article in PLOS Medicine — authored by one of the researchers on the new JAMA Pediatrics study — noted that in Texas in 2016, there were almost 45,000 children with nonmedical vaccine exemptions, which is near double the exemptions given in 2010 and a 19-fold increase from 2003. Those numbers mean that some Texas counties are at risk of having their measles vaccination rate drop below 95 percent, which is the threshold scientists say we need to ensure herd immunity and prevent outbreaks. Right now, 18 states allow “personal belief” exemptions for childhood vaccines.
So, what would a relatively minor decrease in measles immunization look like in the U.S.? To find out, researchers used vaccine data from the Centers for Disease Control and Prevention to simulate county-level MMR vaccine coverage for children ages 2 to 11. They then used a mathematical model to estimate the impacts of decreasing vaccination rates, simulating thousands of situations in which measles is introduced by a traveler into the U.S. (This is the kind of scenario that’s happened in recent real-life measles outbreaks.) They found that a 5 percent decline in MMR vaccine coverage among U.S. children would result in a three-fold increase in national measles cases, or 150 cases and an additional $2.1 million in economic costs to the public sector. That’s $20,000 per case of measles.
The researchers noted that their findings were conservative, as they only accounted for children ages 2 to 11 and not for infants, adolescents and adults who are unvaccinated against measles. Study co-authors Nathan Lo and Peter Hotez write:
The results of our study find substantial public health and economic consequences with even minor reductions in MMR coverage due to vaccine hesitancy and directly confront the notion that measles is no longer a threat in the United States. Removal of the nonmedical personal belief exemptions for childhood vaccination may mitigate these consequences.
In a news release on the study, Hotez, dean of the National School of Tropical Medicine at Baylor University in Texas, added: "I think our study is a wake-up call for what we can expect in the coming months and years as vaccine coverage rates continue to decline in the 18 states that now allow non-medical or philosophical belief exemptions.”
Even though measles was declared eliminated in the U.S. in 2000, outbreaks have recently began occurring on a yearly basis. According to CDC, recent case counts have ranged from a low of 55 in 2012 to a high of 667 in 2014, which represented the greatest number of measles cases since the disease was announced eliminated in the U.S. The agency also noted that the majority of residents who caught the disease were unvaccinated. In the most recent measles outbreak in Minnesota earlier this year, 79 cases were confirmed, the vast majority of which were among unvaccinated children. Research has shown that vaccine refusals do indeed fuel preventable disease outbreaks.
Unfortunately, the anti-vaccine movement got a boost earlier this year when word got out that President Trump wanted to create a “vaccine safety commission” led by Robert Kennedy Jr., who’s known for spreading debunked information about vaccine safety. So far, this idea hasn’t panned out. Let’s hope it never does.
For a copy of the new measles vaccine study, visit JAMA Pediatrics.
Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for 15 years. Follow me on Twitter — @kkrisberg.