Updated June 30, 7:30 p.m. EDT:

On Tuesday, California Governor Jerry Brown signed Senate Bill 277. Beginning July 1, 2016, schoolchildren are to get vaccinated prior to admission on any public or private school in the state, unless they have valid medical reasons.

"It is a great day for California's children," Paul Offit, chief of infectious diseases and director of the Vaccine Education Center at Children's Hospital of Philadelphia, said to USA Today. "Finally, someone stood up for California's children."

The California Senate on Monday passed a controversial vaccination bill that is considered one of the strictest in the country, as it would no longer accept "personal beliefs" as an excuse to opt out of vaccination. Once enacted, schoolchildren would be required to get vaccinated prior to admission on any public or private school in the state, unless they have valid medical reasons.

Senate Bill 277 was proposed during the height of the Disneyland measles outbreak that infected many who visited the theme park in December last year. Public officials confirmed 126 cases in California alone, and most of the victims were unvaccinated.

In May, the Senate voted 24-14 in favor of minor amendments on the bill which got approved last week. A majority of the state lawmakers agreed that the unvaccinated schoolchildren are putting the community in danger.

The bill proposes that only medical exemptions, such as immune system deficiencies, will be accepted as valid reasons to opt out of the vaccinations. Those who opt out due to non-medical reasons will need to enroll their children in a home-based or off-campus school program, the Los Angeles Times reported.

"I've personally witnessed the suffering caused by vaccine-preventable diseases, and all children deserve to be safe at school," said Democrat state Sen. Dr. Richard Pan, the bill's author and pediatrician, according to Reuters. "The personal belief exemption is now putting other school children and people in our community in danger."

Several health and education organizations supporting the vaccination bill are pleased with the Senate's decision, while an opposing group, A Vote for a Choice, said it would collate 50,000 signed petitions hoping that Gov. Jerry Brown would veto the legislation.

Some parents are against vaccinations due to their links to autism and allergic reactions, despite clarifications from medical experts that the benefits of vaccinations outweigh the risks.

"While we are very disappointed in the Senate's vote today, we are hopeful that Governor Brown respects the First Amendment to the U.S. Constitution," Kristen Hundley, president of Our Kids Our Choice, another opposition group, said in a prepared statement, according to the Mercury News.

"We also know that he is a champion of precision medicine, which is in direct conflict with the idea of medical mandates. Precision medicine calls for individualized health care, while medical mandates only permit a one-sized-fits-all approach."

If Gov. Brown decides to enact the bill, California would join Mississippi and West Virginia which also do not accept religious and personal beliefs as opt-out reasons.