The fight against measles in a handful of states is facing staunch opposition from Republicans and anti-vaxx parents as lawmakers crack down on exemptions that let kids skip vaccinations.

The Centers for Disease Control and Prevention reported that through Friday there have been 839 individual cases of measles throughout 23 states. That’s the most cases since 1994, making this the worst measles outbreak in decades. In response, a number of states where it’s spread have been trying to limit exemptions, with efforts mostly led by Democrats.

Washington eliminates personal exemption

Washington state has had more than 70 cases of measles this year, according to the Associated Press. On Friday, Democrat Gov. Jay Inslee signed a bill that removed a philosophical or personal exemption from the requirement that children receive the combined measles, mumps and rubella (MMR) vaccine before attending a school or daycare. A child can still skip a vaccine for medical or religious reasons.

The final bill passed in late April but was contentious the whole way through the state House and Senate. Other versions of the bill were more sweeping in scope, but it eventually settled on removing just the personal exemption for the MMR vaccine. Still, some in the GOP were not pleased, saying it interfered with a parent’s choice.

“Ultimately, the parent is responsible for that child,” Republican Rep. Joe Schmick told The Spokesman-Review at the time.

The CDC and others have pointed out, however, that it’s important a community reach “herd immunity” — the concept that when a high percentage of a population is immunized, it can provide protection to the entire community.

“We should be listening to science and medicine, not social media,” Inslee said at the bill-signing. “It is science and truth that will keep us healthy rather than fear.”

“It is science and truth that will keep us healthy rather than fear.”

Parents protested the bill-signing last week and one suggested to the AP that she and others would just push for a religious exemption now.

"I'm sure many of them are going to switch over," Carolyn Stirling told the AP. "It's pretty much the same idea, really. Whether you call it religion or call it your conscience or personal preference, it's just semantics."

A California bill aims to stop fake exemptions

A proposed bill in California would impose tougher vaccination rules that would give state public health officials the power to decide if a child can skip shots. Proponents of the bill have said it would help stop bogus exemptions. The bill was proposed by Democratic state Sen. Richard Pan and was supported by the California Medical Association and American Academy of Pediatrics.

"If we continue to let these fake medical exemptions increase, we're going to have another larger outbreak, and we need to stop that now," Pan said in April, according to the Associated Press.

The bill has faced angry opposition, however. Vocal critics yelled that Pan was "committing crimes against humanity,” among other insults, at a hearing in April, according to the AP.

The Mercury News reported on Monday that as legislators consider the bill, there has been an effort on anti-vaxx social media pages to spread disinformation about the proposed legislation.

Oregon booted the moral exemption

The Oregon House last week passed a bill that would remove an exemption that allows parents to have their child skip the measles vaccine for moral reasons. As Vice News’ Emma Ockerman wrote, the state’s Republican Party responded with a tweet comparing vaccination requirements to abortion rights.

“Oregon Democrats were just joking about 'my body, my choice' while rammimg (sic) forced injections down every Oregon parent's throat,” the state’s official GOP account tweeted last Monday. The bill would still allow for legitimate medical exemptions.

Meanwhile, the attorney general in Connecticut last week said there was nothing preventing lawmakers in the state from pursuing legislation that would remove a religious vaccine exemption in the state. In Maine, meanwhile, a bill that would remove philosophical exemptions but keep religious exemptions for vaccination requirements passed through the state Senate along party lines early this month. The bills in both states have faced opposition from angry parents and Republican lawmakers.