In Mexico, a sweeping measles outbreak has triggered a sweeping response — a campaign to vaccinate 2.5 million people a week.
In the capital, posters are plastered with QR codes for people to look up the nearest spot for vaccination.
Nurses go door-to-door, and there are pop-up vaccine stations in bakeries, bus stations, cinemas, shopping malls, roundabouts —- you name it. WhatsApp groups are pinged with waiting times at various centers.
"People were very worried," says Erica Briones Chavez, a nurse in a public medical center in Mexico City's Chapultepec neighborhood. "For a couple of months we were doing two to three hundred vaccinations a day — mothers, fathers, teenagers and babies. Even the grandparents wanted to get vaccinated." People were queueing up for two hours.
Some infectious disease experts have lauded the effort. But there are critics. Sergio Meneses Navarro, a researcher at Mexico's National Institute of Public Health, says it's not targeted enough: "At the moment it's a massive response but it's inefficient," he says. "We should be working in the most unprotected regions, with the most unprotected populations."
Are the lines still long?
The campaign to vaccinate remains at emergency-levels, but the reality on the ground is changing.
Nurses at this medical center in Chapultepec say there has been a drop off in interest. And there's also been a drop off in pop-up vaccination spots. At one such location, a train station, the manager, Horacio, shrugged. "Sometimes they come, sometimes they don't," he says about the health workers. "And when they run out of vaccines, they close early."
The outbreak came from north of the border.
Last year, a 9-year-old Mennonite child in the state of Chihuahua fell ill after visiting relatives in a Mennonite community in Gaines County, Texas. Cases ripped through Mexico's largely unvaccinated Mennonite communities — about 40,000 in the state of Chihuahua and 70,000 total in the country, by some estimates. Many of Mexico's Mennonites emigrated from Russia to Canada, and then Mexico, in the 1920s.
With low vaccination rates in their community and patchy coverage in Mexico at large, that measles case translated into a national outbreak.
Measles is one of the most contagious diseases, spreading easily through air droplets, liable to infect up to 90% of unvaccinated people nearby. It can also be passed from one person to another four days before an infected person shows signs of having it. These indicators can include cold and flu-like symptoms, a red rash or white spots inside the mouth. While most people recover within ten days, measles can be deadly for children under 5 or those with severely weakened immune systems.
Since January last year, Mexico has so far seen more than 36,000 suspected cases — almost 15,000 confirmed — and 35 deaths. The government posts daily updates.
"Measles isn't a disease of the past, it's a disease that we have the technology to prevent. That technology is vaccines," says Sergio Meneses Navarro, the public health researcher.
But administering those vaccines is a challenge — two doses are required at least a month apart.
Meneses Navarro says Mexico's measles vaccination rates have dipped below 95% (the herd immunity threshold), and societal inequalities are exacerbating the problems: Poorer communities not only have lower vaccination coverage but also "slower detection of outbreaks, reduced access to health services and less information that would make them aware of the risk of being infected," he says, so disadvantages accumulate.
From praiseworthy to problematic
Mexico's vaccination system was once the envy of health policymakers in Latin America. In the latter half of the 20th century, Mexico provided universal free jabs and had highly visible mass campaigns. Measles was all but eliminated and herd immunity achieved across multiple diseases.
However, in recent years this progress has eroded. The reason: money. The government used to match funding of its public health care system to the growth in the population but no longer does so.
Next came the COVID-19 pandemic, which took a bite out of vaccination rates.
"People avoided leaving their homes and certainly avoided going to the doctors unless they were sick," says Meneses Navarro. So in the early years years of the pandemic, far fewer people received their routine vaccinations, leaving an immunity gap.
Government survey data from 2023 showed only a third of 2-year-olds had received the complete childhood immunization schedule.
Mexico also seems to have been a victim of its own success. Health policy consultant Beatriz Martínez said people became complacent: "As diseases become less visible, people perceive less risk."
The TikTok factor
As in much of the world, Mexico hasn't been immune to the effects of misinformation and vaccine hesitancy.
The nurses at the public health clinic say they've seen a general rise in trepidation surrounding vaccines — and doubts that stem from what people see on TikTok.
They have to spend time answering questions and countering what people have seen online. The nurses hope high-profile government campaigns like the measles effort will reinforce the importance of vaccines in the public mind.
But for some communities, distrust of public institutions runs deep.
"Mexico is a deeply stratified society, with very large inequalities in income, education and health," Menses Navarro says.
He says this contributes sometimes to vaccine hesitancy among rural and indigenous communities where he often works. Some people avoid health services, believing that they spread disease.
This population is also logistically more challenging to vaccinate. In some parts of the country, especially rural or hard-to-reach areas, certain key components for vaccination may be lacking: cold-chain storage for temperature-sensitive vaccines, a stable supply of the vaccines and trained staff.
Mexico also doesn't have a central immunization register, giving authorities no oversight on who has and hasn't been vaccinated.
"That makes it much harder to target interventions," says Meneses Navarro. "You end up vaccinating broadly but not always efficiently."
And at the health center in Chapultepec, the nurses interviewed for this story stress that more people need to come for that first shot — and worry that folks won't return for that second dose.
Katie Silver reports on health and science around the globe — from obstetrics in Sydney to genomic sequencing in London to climate change in Indonesia. After a decade at the BBC, she's currently based in Mexico City. She pops up on X @katie_silver.
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