Fox News medical contributor Dr. Nicole Saphier breaks down the spread of measles cases and the 'emotionally charged' debate over vaccines.

The Mennonite population being affected by a measles outbreak in West Texas is part of a larger, loosely affiliated group of churches worldwide with varied beliefs and leadership structures — and with sometimes strained or distant relations with health officials and other public authorities.

A measles outbreak in Canada's Ontario province continues to grow, with health officials reporting more than 140 cases on Thursday, making it the most severe outbreak in decades.

Measles was considered to be eliminted in the U.S. in 2000, thanks to vaccine developments. But vaccination rates have dropped since the covid pandemic began.

Vaccines are the most effective tools to combat measles. Breakthrough cases — infections among the vaccinated — are extremely rare. But as outbreaks spread, it’s important to review your own vaccination status and make sure you are properly protected.

"Measles was rare in the United States, but outbreaks are occurring in areas where vaccination rates have fallen," the American Academy of Pediatrics said in a statement. "Most children who get measles are not up to date on recommended vaccines or are not old enough to get measles vaccine."

New measles cases have been confirmed in New Jersey and Kentucky with the one common factor being a lack of measles vaccinations.