As US measles cases climb into the thousands, immigration has become part of the political debate over the cause. Outbreak data point to a more complex picture involving international travel, declining vaccination coverage, pockets of susceptible populations, and highly efficient measles transmission. CDC reported 3,294 confirmed cases as of September 10.
As measles infections continue to mount across the US and deaths are starting to occur, there is an increase in social media postings along with political appearances to shift the blame from federal policies, which discourage vaccine usage, to illegal immigration. The underlying thesis of these attacks is that the skyrocketing measles cases are due to a surge in illegal immigrants carrying the virus.
Top 3 Takeaways
A third measles-related death has been reported in Pennsylvania. A 40-year-old Jefferson County woman died from complications associated with measles, according to the county coroner, while the Pennsylvania Department of Health reviews the case.
The latest fatality underscores that measles can cause severe disease. Complications can include pneumonia and encephalitis, and deaths can occur even though measles is vaccine-preventable.
Health care preparedness remains critical. Infection preventionists should reinforce rapid identification, airborne precautions, appropriate isolation, exposure management, and verification of health care personnel’s immunity.
Representative Byron Donalds (R-FL) on Face the Nation (August 23, 2026) stated: “The reason why we have seen a measles outbreak in certain parts of the country is because of rampant illegal immigration into the US from the previous administration.” They stated that “People have come into the country illegally, have not had that vaccination schedule, and not the ones today on young kids that parents do have concerns about.”
However, it is hard to attribute the primary driver of the rise in measles cases in the US to illegal immigrants when the Trump Administration is touting immigration control of the border as “promises made, promises kept.” The White House states that “...the US had negative net migration in 2025—the first time in at least a half-century.” According to the WHO, the surge in measles cases in the US began in 2025 and increased in 2026 (Table 1).
Regardless of legal status, international travel has been an important source of measles outbreaks in the US. This was the case with the measles outbreaks in Orthodox Jewish Communities in New York and New Jersey in 2018-2019.
There are also outbreaks attributed to “migrants.” In March and April of 2024, there was a measles outbreak involving 64 confirmed cases in a Chicago migrant shelter.
However, the source of the large 2025 measles outbreak in West Texas (Gaines County) is unknown, and Texas’s Health Service Commissioner, Jennifer Shuford, MD, MPH, testified that she did not have “any data that would say yes or no” on whether immigrants caused the outbreak. Shuford also noted that measles vaccination rates had fallen, making the area a prime target for an outbreak. During this time, there were also 4 unrelated cases involving international travel.
Vaccination rates in many South American countries are higher than in the US. Unfortunately, vaccination rates in the US are declining. The percentage of US counties achieving the 95% measles vaccination rate required for herd immunity has dropped from 50% to 28%.
Twenty-seven countries are listed as having vaccination rates of 99%. Johns Hopkins Bloomberg School of Public Health reports the US measles vaccination rate (MMR) at 92%.
In addition, vaccination rates across the US are not uniform; they vary widely. And those who do not believe in vaccinations often share common religious or political beliefs and tend to congregate with one another.
There is little doubt that diseases can enter through our border. The COVID-19 pandemic has taught us that borders are leaky, and the more infectious a virus is, the harder it is to prevent its entry into a country. With highly infectious diseases, even one person can cause a massive outbreak. Measles is the most infectious disease known to humanity, even more so than COVID-19.
Two years ago, measles was not a major issue in the US. Now, we are on the verge of losing our measles elimination status. Borders are leaky, and focusing on international travel is important. Still, it makes little sense to focus on illegal immigration as the primary driver of outbreaks during a time when illegal immigration is falling, and rates of measles are skyrocketing.
In addition, legal international travelers, both US citizens and foreign visitors, are not required to receive vaccination and too often have been documented as the source of measles outbreaks.
As I have repeatedly stated, we do not live in a fishbowl, which is why public health is so vitally important. Vaccinations are key to regaining our society’s measles protection. Our federal government needs to resume tracking vaccination rates and promote the highly effective, time-tested measles vaccine.
