At a hearing intended to reassure Americans that vaccinations are safe, Sen. Bill Cassidy (R-La.) suggested that the worst measles outbreak in decades is the result of undocumented immigrants, not conspiracy theories about medical practices.

“Tell me, of those infected in the California epidemic, how many were native born Americans and how many had immigrated here?” Sen. Cassidy asked in Tuesday’s hearing on vaccinations before the Senate Health, Education, Labor and Pensions Committee.

Dr. Anne Schuchat, the Director of the Centers for Disease Control and Prevention’s top official on immunization, admitted that she didn’t have the exact numbers, but reminded the senator that “most of the importation that we have of measles each year are in Americans who are traveling abroad and come back.”

She noted that during the ongoing measles outbreak, the virus has spread “in some of the wealthier communities,” not immigrant enclaves.

In opening remarks, the chairman of the committee, Sen. Lamar Alexander (R-Tenn.) noted how in some of those areas of Los Angles, as many of 70% of parents at certain school have opted out of vaccinations for their kids.

There you’ll find “vaccinations rates are as low as those in Chad or South Sudan,” said Sen. Alexander.

Sen. Cassidy, however, was skeptical.

“We’ve heard a lot about how the families from wealthy communities of Santa Monica and the west side of Los Angeles are not vaccinating the children,” he said, “but is that where we’re seeing these cases?”

A licensed physician, Cassidy added that he did his residency in Los Angeles, and that “there are a lot of immigrants and a lot of those immigrants may have fallen between the cracks.”

Dr. Schuchat said that although there was substantial importation of measles from Latin America “years ago,” the region “really took on the elimination of measles” and “had great success.”

According to data from the World Health Organization, vaccination rates in Latin America are now in-line with the United States where 91% of 1-year-olds are vaccinated. In El Salvador, the number is higher, at 94%.

Further belying Sen. Cassidy’s suggestions, the CDC looked into 288 cases of measles between January and March last year, and discovered that 45 were a result of “direct importation.” Forty of those cases were a result of Americans traveling abroad and returning, as Dr. Schuchat testified, and only three came from the Americas.

Sen. Cassidy is not the first lawmaker to draw the non-existent link between the recent measles outbreak and immigration.

Speaking on a radio program earlier this month, Rep. Mo Brooks (R-Ala.) claimed that diseases “brought into American by illegal aliens” in Central and South America have “caused deaths of American children over the past six to nine months” and said Latin American migrants “might be [behind] this measles outbreak.”