Two California lawmakers, Democratic U.S. Sens. Barbara Boxer and Diane Feinstein, have sent a letter to the state’s Health and Human Services Secretary urging that California do away with all personal and religious beliefs exemptions to immunizations. The recent outbreak of measles that originated at Disneyland in California has state legislators looking at changes, and the two senators are urging the end to all exemptions except medical.

In recent weeks, with the spread of measles throughout 15 states, immunizations of children have been closely scrutinized, and the debate of whether vaccinations should be required has flared hotter than ever. Most states allow parents to decide whether to vaccinate or not. Although all states require school-aged children to be immunized against certain diseases, many offer exemptions that allow parents to opt out.

A small minority of parents still refuse to allow their children to be vaccinated due to fears about potential side effects of vaccines. The research that led to this belief has since been debunked, but many still worry about risks.

In California, as well as some other states, parents can refuse to vaccinate their children by saying they do not believe in vaccination and showing proof that they have consulted with a doctor, or based on religious belief, which does not require a doctor consultation. In their letter Boxer and Feinstein stated that they think both exemption options are flawed, and that they oppose “even the notion” of a medical professional helping waive a vaccine requirement, outside of a medical reason.

Democratic California State Sen. Richard Pan, who is also a pediatrician, said on Wednesday that he plans to introduce legislation that would end the states exemptions, although he did say he would consider discussion about continuing to allow opting out for religious reasons.

According to California public health officials, 92 people have been diagnosed with measles in the state, with more than a dozen other cases confirmed in 19 other U.S. states, as well as Mexico. In 2000, measles was declared eradicated in the U.S. after decades of consistent childhood vaccines. The nation had its highest number of measles cases in 20 years in 2014.