The United States has seen a rise in rates of the illness in recent years, as anti-vaccination voices have gotten louder. This year has seen the highest measles infection rates since the 1990s, according to the Centers for Disease Control and Prevention.

Medical ethicist Art Caplan joined Boston Public Radio on Wednesday to advocate for mandatory vaccination regulations.

"If you let vaccine rates dip, and they don't have to dip that much below 90 percent, you start losing what's called herd immunity, meaning it's easier for the virus ... to jump from one person to another, you could have a disaster," he said.

Health officials attributed the largest outbreak this year to one in New York. Most outbreaks have occurred in small communities with low vaccination rates, according to the CDC.

"Massachusetts would be wise to follow the lead of California and New York and get rid of the religious exemption" for vaccinations, he said. "People may be thinking, 'Don't people have a right to their religious beliefs? Isn't that a fundamental constitutional right?' ... The Supreme Court, both in Mass. and ultimately the U.S. Court, said look, if you're endangering the public health, there is a right to restrict religious liberty."