Republican politician Byron Donalds has attributed recent U.S. measles resurgences to undocumented immigration.
WASHINGTON, DC: As the nation experiences a resurgence in measles cases, medical professionals have pointed to dropping rates of the measles, mumps, and rubella (MMR) vaccine as the primary driver behind the spread.
Amid these public health concerns, Republican gubernatorial candidate in Florida, Byron Donalds, pointed the finger at undocumented immigration under the Biden administration. Donalds argued that “rampant illegal immigration” is directly responsible for the localized outbreaks. Here is a look at the facts surrounding that statement.
The Statement: Byron Donalds Points to Undocumented Immigration
Brennan: “Nearly all of Florida is below the 95% immunization rate for herd immunity for measles. So, is your message to Florida parents to get your kids vaccinated?”
Byron Donalds: “No. My message is the reason we have seen a measles outbreak is because of rampant illegal… pic.twitter.com/Q1lVsTvkwP
— BulwarkClips (@BulwarkClips) August 23, 2026
Appearing on CBS News’ ‘Face the Nation’ on August 23, host Margaret Brennan highlighted that immunization coverage in Florida has fallen below the 95% threshold required to maintain community herd immunity for measles.
When Brennan asked Byron Donalds if he would encourage parents in Florida to have their children immunized, he declined to do so.
Instead, Donalds responded, “No, actually my message to Floridians and, quite frankly, to Americans is the reason why we have seen a measles outbreak in certain parts of the country is because of rampant illegal immigration into the United States from the previous administration.”
Donalds asserted that individuals crossing the border unlawfully had missed out on standard MMR immunization schedules, stating, “So the key thing is, you number one, you got to control immigration into your country. You can’t have an entire segment of people, more than 10 million, coming to your country without that vaccination schedule.”
Fact Check: The Argument Lacks Supporting Evidence
This narrative is false. There is no factual basis linking unauthorized immigration to the domestic spread of measles.
Furthermore, the assertion that more than 10 million individuals entered the country unlawfully during the Biden administration is inaccurate.
Federal authorities permitted roughly 4.3 million people to enter the U.S. pending their scheduled immigration proceedings. That administrative statistic does not equate to unauthorized entry, nor does it mean those individuals lacked immunizations.
Public health specialists emphasize that shrinking domestic immunization rates are the primary culprit behind rising measles cases. Data shows that roughly 94% of confirmed measles patients in 2026 had either never received the shot or had an unknown immunization history.
The total number of measles cases recorded in 2026 has already surpassed the figures from 2025, which had marked the highest annual total since 1991. Highly contagious by nature, measles can lead to severe health complications, such as pneumonia, brain inflammation, and fatalities.
The Centers for Disease Control and Prevention (CDC) advocates for a two-dose MMR regimen, which provides roughly 97% protection against the virus. Because federal health agencies do not collect data on the immigration status of patients who contract measles, there is no statistical evidence to support claims that unauthorized arrivals are driving the ongoing transmission.