The measles outbreak in the United States has grown to worse affecting at least 135 individuals in 14 states, over half of whom are in California prompting some lawmakers to mull on the rules that allow parents to opt out of getting their children vaccinated.

On Wednesday, a group of lawmakers announced a legislation that could abolish the exemption from mandate to get children vaccinated before they enter school should this conflict with the personal beliefs of their parents.

The five lawmakers said in a Capitol news conference that such legislation would address a trend among parents of opting out their children from getting immunized against common diseases and concerns over the spread of infectious but preventable diseases such as measles and whooping cough.

California State Senator Richard Pan, a pediatrician, pointed out that there is not enough number of individuals who were vaccinated to contain the diseases. An action is imperative before more children get sick or die.

"Parents are letting us know that our current laws are insufficient and don't protect their kids," Pan said. "I hope we don't have to wait for someone to die before we take this seriously."

The proposed legislation will apply to children who attend public or private schools. Completely home-schooled children, however, are not addressed by the mandate.

The proposed law will likewise still allow children not to get vaccinated because of medical reasons such as for having a weak immune system and allergic responses.

The number of children who have personal belief affidavits on file is 13,592, 2,764 of whom were based on religious beliefs. Pan said that once the bill is passed, the religious exemption would become null. The lawmakers though said that he is open to have a separate conversation on this issue.

The proposed legislation was drafted after over 90 measles cases have been reported in California with most of the cases associated with visitors or employees at Disneyland and those who have come in contact with them.

Nineteen states in the U.S. currently allow parents to refuse vaccination of their children based on personal beliefs. Forty-six states permit exemptions based on religious beliefs and only two states, Mississippi and West Virginia, do not allow exemptions except for medical reasons.

The bill already has its critics who cite parental rights, religious freedoms and concerns over the safety of vaccines.

"While medical experts are overwhelmingly in agreement that vaccines are safe, preserving the freedom of choice has also emerged as part of this important discussion," said Senate Republican leader Bob Huff of Diamond Bar.