Measles Cases Surge 1,940% in Mexico’s Yucatan Peninsula

Quintana Roo, Mexico — Measles cases across Mexico’s Yucatan Peninsula have soared nearly 1,940% in a year, climbing from 22 confirmed infections in 2025 to 449 so far in 2026, according to health data.

Quintana Roo accounts for the bulk of the diagnoses with 389 cases, while Yucatán has recorded 42 and Campeche 18. The virus is still circulating: between September 18 and 25, authorities confirmed 10 new infections — seven in Quintana Roo, two in Yucatán and one in Campeche. The pattern matches the trend seen in recent months, with Quintana Roo reporting new cases every week since August.

Where the Cases Are Concentrated

The sharpest shift occurred in Quintana Roo, which had logged only two cases at the same point in 2025 and now stands at 389.

Yucatán also climbed, from three cases to 42. Campeche behaved differently, going from 17 in the comparable 2025 period to 18 this year.

The regional increase was driven mainly by Quintana Roo, a state marked by high population mobility because of its tourism industry and its national and international connections.

Mobility can help introduce the virus into new areas, but sustained transmission chains also require susceptible populations — chiefly people who are unvaccinated or have incomplete immunization schedules.

The rise has been steady. By late July, the peninsula had accumulated 321 cases and was already reporting an increase above 1,300%, a figure that kept growing through August and September.

Why Cases Keep Rising

Lapsed vaccination schedules are among the factors specialists link to the resurgence of the disease.

Infectious disease specialist Alejandro Muñiz said coverage began to decline before the COVID-19 health emergency and the problem deepened during the pandemic, when fewer people sought medical care and many schedules were left incomplete.

“Yes, the situation we have now is because we haven’t vaccinated enough,” he said.

When a large share of the population is protected, the virus struggles to find susceptible people. The problem emerges as the number of children, adolescents and adults missing the necessary doses grows.

The Health Ministry (Secretaría de Salud) reported that although national transmission continues on a downward trend, 19,559 accumulated cases had been confirmed between February 2025 and September 17, 2026, with 34 still active.

Who Should Get Vaccinated

The vaccination drive is not aimed only at children. The federal strategy targets girls and boys who need to start or complete their doses, as well as people aged 13 to 49 who have never been vaccinated or have an incomplete schedule.

For adolescents and adults, the schedule includes the SR vaccine against measles and rubella up to age 49 where protection needs to be completed. The Health Ministry also maintains an online platform for locating measles vaccination sites.

In Quintana Roo, authorities have stepped up their response this year, intensifying measles vaccination campaigns since February as infections grew.

Nationally, the Health Ministry reported in September that more than 36 million measles vaccines had been administered as part of the effort to contain transmission.

How Easily Does Measles Spread?

Measles is highly contagious, which means the presence of unprotected groups makes it easy for the virus to seed new infections within a community.

While the disease has historically hit children hardest, incomplete schedules also leave adolescents and adults exposed.

The 10 new cases recorded on the peninsula between September 18 and 25 show that regional transmission continues despite the decline seen at the national level.

With 449 diagnoses against 22 a year earlier, the roughly 1,940% increase reflects a very different picture from 2025 and keeps vaccination, early detection and epidemiological surveillance as the main tools for breaking new chains of infection.