Vaccination Opt-Outs Have Declined in Many US States

Despite well-publicized concerns that parents are not getting their children vaccinated in parts of the US, the Centers for Disease Control and Prevention (CDC) found that by kindergarten age, the vaccination rate for the current school year is 90% or better in all but three states and Washington, DC.

This year 22 states had a vaccination rate for entering kindergartners of at least 95% compared to 17 states last year.

Reporting in this week’s issue of Morbidity and Mortality Weekly Review, Ranee Seither, MPH and colleagues found that during the 2015-2016 school year, median vaccination coverage for more than four million US kindergartners was 94.6% for two doses of measles, mumps, and rubella (MMR), 94.2% for diphtheria, tetanus and pertussis (DTaP) and 94.3% for two doses of varicella.

Eight states included data for some home-schooled kindergartners, which could explain why the vaccination rate was not even higher. Some parents home-school their children to avoid meeting vaccination requirements. The CDC numbers also included non-vaccinated children whose parents got an exemption, either medical, religious, or philosophical.

States set their own requirements for vaccination, including whether they allow children medical or religious and philosophical exemptions.

But these opt-outs are growing less popular in many states, the CDC found. In 16 states there was a lower percentage of exemptions this year than last, while it remained unchanged in 8 states. The overall exemption rate went up slightly nationally, but the researchers attributed that to a statistical change: some states that had not reported that data last year did so this year.

In the state of Michigan, non-medical exemptions decreased by 1.7%.

In California opt-outs dropped by 0.2%.

In Michigan the drop might be because of a new state rule requiring parents who request exemptions to receive health education at a county health department about the risks of getting vaccine-preventable diseases, the authors noted.

Measles outbreaks in 18 states in 2015 might also have contributed to higher vaccination rates, they added.

The number of states with vaccination exemption rates of greater than 4% decreased from 11 states in 2014-2015 to nine in 2015-2916. The states with the highest rates of exemptions for any cause were Idaho (6.1%), Oregon (6.3%) Alaska (5.9%) and Vermont (5.7%).

Among states that reported the grounds for parents claiming exemptions, the median percentage of medical exemptions was 0.2% and non-medical exemptions had a rate of 1.6% (the highest was in Oregon at 6.2%).

The numbers show progress but there’s more to do, the team noted. “Although state-level vaccination coverage is high and exemptions are low, some children in kindergarten remain undervaccinated.”

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