with weaker, non-medical exemption policies for vaccinations can reduce the
likelihood of a measles outbreak 140 to 190 percent by strengthening them, a
new study from the University of
Colorado Anschutz Medical Campus shows.
said the magnitude of those outbreaks can also be cut in half by strengthening
exemption policies for children.
the year 2000 measles was no longer being transmitted in the U.S.,” said the
study’s lead author Melanie Whittington, PhD., a health services researcher.
“Compare that to 2015 when we had over 150 cases in the first three months.
Suddenly measles is an issue again despite having an effective vaccine.”
and her colleagues, including the study’s senior author Jonathan Campbell, PhD,
associate professor of clinical pharmacy at the CU Skaggs School
of Pharmacy and Pharmaceutical Sciences, wanted to find out why.
mathematical models, they simulated the magnitude, likelihood and cost of a
measles outbreak under different non-medical vaccine exemption policies.
state has such policies. Those with “easy” exemption policies typically only
require a parent signature on a standardized form. States with “medium”
exemption policies require parents to obtain a form from a health department
and/or attend an educational session on vaccinations, or write a statement of
objection. Finally, states with “difficult” exemption policies require parents
to get a standardized form or statement of objection notarized.
researchers, using data from the Centers for Disease Control and Prevention’s
National Immunization Study, found easier non-medical vaccine exemption
policies to be associated with a greater risk for outbreaks of
state they modeled was Colorado, which has one of the lowest vaccination rates
for measles. Only 87.4 percent of children between the ages of 19-35 months are
covered. And 5 percent of kindergartners report an exemption.
modeled an environment where the population had low vaccination coverage and
then simulated measles outbreaks under different exemption policies,” said
Whittington. “We found that a state like Colorado is 140 to 190 percent more
likely to experience an outbreak with an easy exemption policy than if it had a
medium or difficult non-medical exemption policy. The outbreak size can
also be reduced nearly by half with stronger policies.”
the researchers focused on measles, strengthening exemption policies could
benefit other vaccine-preventable diseases, such as mumps.
is a tradeoff here,” said Campbell, who specializes in pharmaceutical outcomes
research. “It’s a trade between freedom and risk. Are we willing to give up a
small piece of freedom that nudges us toward vaccination in order to halve the
risk of a detrimental outbreak of a preventable disease? I think Colorado
should be willing to make that trade.”
researchers urged the strengthening of non-medical exemption policies as a way
to increase vaccination coverage.
are not saying you can’t have non-medical exemptions,” Campbell and Whittington
said. “But if we strengthen them, we can improve health and reduce the economic
impact of a potential outbreak.”
study was published online this month in Academic Pediatrics.
include Allison Kempe, MD, MPH; Amanda Dempsey, MD, PhD and Rachel Herlihy, MD,