For the first time, Washington state’s child immunization rate is above the national average.

That is huge. The state had been dead last among states because of easy opt-out rules.

Credit a new law passed by the Legislature last year. Parents who used to only have to sign a form claiming religious, philosophical or personal reasons against vaccines, must now get a doctor’s signature to skip immunizations. In the year since lawmakers tightened up exemption rules, the vaccine opt-out rate has fallen by a quarter, according to the state Health Department.

That’s after the opt-out rate doubled over the 10 years before the 2008-09 school year — to 7.6 percent.

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Tightening the rules was the right thing to do. Despite long-standing laws requiring children to be vaccinated before entering school or day care, parents skipped vaccines for their children for a number of reasons, including convenience and erroneous information and a now-discredited study linking vaccines to autism.

The work isn’t done, especially when it comes to immunization rates for older children. Teens spend a lot of time around young children, in their families and through jobs baby-sitting or tutoring.

A study in the New England Journal of Medicine noted that more parents are opting out of vaccines, particularly in states where opt-out rules are lax.

Washington has reversed a troubling record and should be viewed as a model.