The U.S. is facing its largest measles outbreak in decades. With over a thousand cases reported nationwide and hotspots like Texas surpassing 700 confirmed infections, health officials have been quick to cite two culprits: declining vaccination rates and international travel. But missing from this otherwise detailed picture is a critical data point—immigration status.

The Centers for Disease Control and Prevention (CDC), along with state health departments, does not collect or disclose whether infected individuals are in the country legally. This omission raises a concerning question: how can the CDC definitively assert that international travelers and vaccine-hesitant Americans are the principal drivers of the outbreak if one of the largest migrant surges from developing nations in U.S. history remains unaccounted for?

What the CDC Does Say

The CDC’s reports emphasize that nearly all measles cases in 2025 occurred among individuals who were unvaccinated or whose vaccination status was unknown. In Texas, where the outbreak is most severe, 95% of infected individuals fall into that category. Some of these outbreaks have been localized in communities with historically low vaccination coverage, such as the Mennonite population in Gaines County. The agency also notes that most "imported" cases are among U.S. residents who traveled abroad and returned infected.

But what’s left unsaid is just as important as what’s disclosed. Nowhere in the CDC's published analysis is there mention of whether any infected persons are recent migrants from countries where measles vaccination rates are dramatically lower than the U.S. average, or where health infrastructure is strained or nonexistent.

The Unasked Question

If immigration status is neither recorded nor disclosed, how can public health officials determine with certainty that migrants are not contributing significantly to the resurgence? More than 2.5 million encounters at the southern border were reported last year alone—many involving individuals from countries with limited access to vaccines. This reality isn’t xenophobic; it’s epidemiological.

Public health guidance requires data, and data gaps this significant may have profound consequences. In omitting immigration status from its surveillance and analysis, the CDC effectively eliminates a variable that could help clarify the root causes of outbreak clusters—especially in cities where large numbers of recent migrants are housed in temporary shelters under crowded and often unsanitary conditions.

In fact, one such localized outbreak occurred in a Chicago migrant shelter in 2024, with 57 confirmed measles cases traced back to the facility. While the CDC responded with targeted vaccination efforts, the agency framed the episode as an isolated incident—again, without broader exploration of how frequently similar patterns might be occurring elsewhere.

A Politicized Approach?

This omission prompts broader concerns about politicization. Under President Trump’s administration, skepticism toward the CDC grew, particularly after inconsistencies and reversals in COVID-19 guidance. Critics at the time accused the agency of allowing political pressure to influence public health messaging.

Today, some may argue the CDC is again downplaying politically sensitive issues—choosing not to explore the immigration link in order to avoid controversy. But this risk-averse approach may come at the cost of clarity and preparedness. If the goal is to protect public health, shouldn’t all plausible vectors of transmission be studied with equal rigor?

To be clear, not all migrants are unvaccinated, and not all unvaccinated individuals are migrants. But refusing to examine the potential intersection leaves the public with an incomplete understanding of the outbreak’s origins and trajectory.

Public Health vs. Public Relations

Epidemiology depends on transparency. When agencies withhold data—or never collect it in the first place—they undermine trust, especially in a hyperpolarized political climate. Americans deserve to know whether their public health agencies are following the science or following the politics.

The CDC has long served as a cornerstone of disease prevention and health communication. But if its messaging appears curated to avoid uncomfortable truths, even well-intentioned public health campaigns may lose credibility.

With the U.S. still reeling from the political battles of the pandemic, perhaps it’s time for the CDC to recommit to data over diplomacy—and let the facts lead wherever they may.