It's easy to opt out of vaccination in Minnesota. All you need do is provide a notarized statement saying you don't want your child immunized.
That's how the clear majority of kindergartners who skipped the measles vaccine this year were able to avoid the shot.
Only 95 current Minnesota kindergartners didn't get the vaccine because of an allergy or other diagnosed medical problem, according to the state Department of Health.
But 1,968 kindergartners weren't immunized against measles just because their parents didn't want them vaccinated.
When vaccination rates rise, the likelihood of a measles outbreak decreases and the highly contagious disease can be at bay. That said, some parents want the state to make vaccine exemptions more difficult to get.
Despite pushes to tighten state vaccine policy, Minnesota lawmakers have shown little inclination to change anything.
Rep. Mike Freiberg, DFL-Golden Valley, has a vaccine bill that's repeatedly failed to gain traction in the Legislature. His proposal would require parents to hear a doctor detail vaccine safety information from the Centers for Disease Control and Prevention before opting out.
He thinks that would go a long way toward increasing immunization rates.
"If you make it at least as inconvenient, frankly, for them to not get vaccinated as it is to get vaccinated and in the process provide them with medically accurate information, then I think it's very likely that they will actually get their children vaccinated," Freiberg said.
Freiberg hopes the ongoing measles outbreak will persuade lawmakers his bill would improve public health in Minnesota. He said Republicans who control the Legislature have shown a willingness to take a closer look at his proposal next year.
This year's measles outbreak may have a profound impact on debate over changing the law next year.
• Graphic: This year's measles outbreak has more cases than the past 20 years did combined — by a lot
In California, a non-fatal measles outbreak that started at Disneyland in 2015 led the state to clamp down on vaccination. Parents pushed for change, and state law now requires medical justification for a child to skip the shots.
Dr. Richard Pan, a pediatrician and California state senator, helped pass the law. He said Minnesota parents should demand the change that California made.
Most parents support vaccination, Pan said, so he thinks they need to organize and tell lawmakers they want change.
"It is unacceptable that we allow a small minority of people to allow spread of disease in our community. That's what happened in California," Pan said.
Vaccine opponents in Minnesota promise to fight any steps to make vaccination mandatory. There's a relatively small, but vocal, cadre of groups linking measles vaccination with health problems and autism — despite widely accepted science to the contrary.
Leo Cashman, who heads the Minnesota Natural Health Legal Reform Project, said requiring vaccination tramples on parental rights.
"We are opposed to any attempt to weaken the parental right to choose on the question of the child's vaccinations," he said.
That's not how many parents see it, though. Ruth DeFoster, a 32-year-old mother of three in St. Paul, said every kid that can tolerate the vaccine should be required to get it.
"When people start opting out because they feel like it or they're afraid, then you start to see what's happening now," Defoster said. "The last time there was a measles outbreak in Minnesota, three children died."
DeFoster's 4-year-old twin boys and their 11-year-old brother are immunized, but there's still a statistical chance they could contract measles. The vaccine is about 98 percent effective at warding off the highly contagious disease.
"Vaccination only works when everyone who can get vaccinated is vaccinated," DeFoster said.