Measles outbreak in Mexico City triggers mass vaccination campaign

In a matter of weeks, Mexico City has transitioned from a scenario of controlled surveillance to an active phase of measles transmission. Confirmed cases have escalated from just six to 107, driven by a community outbreak localized in an area with low vaccination coverage and by intense mobility recorded during the December holiday season.

“For a long time, almost 13 weeks, we had six measles cases. Then we had this community outbreak in Álvaro Obregón and the entire December season, when there were many visits and movements. And one thing that is very important is that 89 percent of the people who have had measles were not vaccinated,” explained Nadine Gasman Zylbermann, Secretary of Health of Mexico City, to MILENIO.

In an interview, the official confirmed that, in addition to the 107 confirmed cases, the surveillance system has analyzed more than 1,130 people with exanthematous disease, reflecting an intensive active search to detect possible transmission chains. To date, the capital has not recorded associated deaths.

Main Outbreak Foci

The main foci of the outbreak are concentrated in Álvaro Obregón and Gustavo A. Madero, although cases have also been identified in Cuauhtémoc, Cuajimalpa, and Miguel Hidalgo, boroughs with high population density and elevated daily mobility.

“We have very important epidemiological controls. Most have been in Álvaro Obregón, in Gustavo A. Madero, in Cuauhtémoc, Cuajimalpa, and Miguel Hidalgo. Especially Álvaro Obregón and Gustavo A. Madero concentrate more cases,” specified Gasman.

A Metropolitan-Scale Health Deployment

Since the first case with symptoms was detected in August, the Mexico City Health Secretariat activated one of the broadest epidemiological surveillance operations in recent years.

As of the most recent report, 423 epidemiological controls have been carried out, with visits to more than 10,600 blocks and over 358,000 homes, with inter-institutional participation from the local health system, health jurisdictions, and IMSS Bienestar.

“We have worked to identify probable cases, conduct examinations, and study people’s movements to understand how the virus has moved,” detailed the secretary.

The operation includes contact tracing, clinical follow-up, sample collection, house-to-house vaccination, and monitoring in high-traffic public spaces such as schools, parks, collective transport, and markets.

Mass Vaccination to Break Transmission

The central strategy to cut the spread is accelerated vaccination. In recent months, more than 833,000 doses of the triple viral vaccine have been administered, with a goal close to one million to achieve coverage of at least 95 percent and achieve so-called herd immunity.

“Our goal is to reach a coverage of 95 percent. We calculated that we had to administer around one million doses and we are very close to achieving it,” explained Gasman.

The campaign is not limited to health centers. Mobile brigades have reinforced immunization at airports, bus terminals, Metro stations, penitentiary centers, and high-mobility points, with special attention to people who do not have complete vaccination schedules.

“We vaccinate people deprived of liberty, we reinforce vaccination at airports and bus terminals, at metro stations, in places where there is a large influx of people,” she emphasized.

Although no infections have been detected in the homeless population, authorities maintain preventive operations to avoid outbreaks in vulnerable groups and mobile populations.

Infection Profile Breaks the Childhood Myth

Contrary to traditional perception, measles is not exclusively affecting minors. The majority of confirmed cases are concentrated in adults between 25 and 44 years old, as well as in girls and boys who do not have complete vaccination schedules.

This pattern exposes an accumulated lag in coverage during previous years, particularly after the disruption of health services during the pandemic.

“Vaccination is no longer just for children. Today we talk about vaccination throughout the life course: young people, adults, pregnant women, and older adults,” emphasized the secretary.

Authorities reiterated that the first dose is administered at 12 months, the second at 18 months, and a booster at six years, in addition to boosters for the adult population between 10 and 49 years old.

Although it is not considered an uncontrollable massive outbreak, the Health Secretariat acknowledges that there is active circulation of the virus in the city.

“The virus is finding unvaccinated people and is transmitting. We do not have a large outbreak as could occur in a city with low coverage, but we are busy limiting transmission,” warned Gasman.

Metropolitan connectivity with the State of Mexico and interstate mobility have facilitated the importation and redistribution of cases, in a context where North America has recorded significant resurgences.

Latent Risk: Possible Loss of Elimination Certificate

The increase in cases rekindles the discussion about the possible loss of the measles elimination certificate, a health status that Mexico achieved after decades of control.

“It would be serious if we were not doing anything. Obviously we want to maintain this certificate. In the United States and Canada they have even extended the deadline. The important thing is to avoid sustained transmission because it is a highly contagious disease,” stated the official.

Specialists warn that the impact of losing the certification is not only symbolic: it implies a greater risk of case importation, international pressure, adjustments in health protocols, and effects on international mobility.

The 2026 World Cup: Reinforced Surveillance

With the proximity of the 2026 Soccer World Cup, Mexico City will strengthen epidemiological surveillance, international health, and vaccination modules at entry points.

Additional training for airport personnel to identify symptoms, installation of vaccination modules for travelers, and immediate care protocols for suspected cases are planned.

“The priority is to protect the health of those who visit the city and take advantage of the event to promote prevention and vaccination,” Gasman advanced.

Authorities reiterated the call to complete vaccination schedules, verify vaccination cards, and go to any health center, regardless of health insurance affiliation.

“The most important message is that we want to invite the population to continue getting vaccinated,” insisted the secretary.