Health through Walls
Transforming Correctional Healthcare Around the World
In the margins of society, entire populations are deliberately forgotten. We like to think we've outgrown some of our inhumane roots, but that’s an illusion born of blinders—ones we wear without realizing, shielding us from the decay in the forgotten corners of the world.
One such corner is a sweltering concrete cell in the Caribbean Haitian heat, built for 18 but crammed with over 70 men. Limbs tangle, heads press against rusted bars, seeking relief from the stench of sweat, waste, and relentless coughing. There’s no space to move, no hope of freedom, and for years, medical care was more myth than reality.
Eventually, someone came. Not with a grand solution or sweeping promise, but with eyes open and sleeves rolled up.
Dr. John May doesn't fit the image most people probably carry of a restless healthcare innovator. Soft-spoken and even-tempered. After graduating from internal medicine residency in Chicago, he found himself doing medical work in the local Cook County Jail—a curiosity that soon became a calling.
In 1999, a 60 Minutes segment aired on the abysmal conditions inside Haitian prisons. The footage was hard to watch. Skeleton-thin men, eyes sunken—a system in true despair. John saw it and couldn’t let it go. He got on a plane and went to see it for himself. What he found was somehow worse.
By the early 2000s, he was traveling to Haiti nearly every month, paying out of pocket, carrying with him a few supplies and a growing sense that something more needed to be built. He wasn't working with any specific group or existing NGO doing this work—he just figured it out for himself. Over time, he started to notice something. It wasn’t just that care in correctional settings was inadequate. It was that entire populations had been structurally written out of public health plans. In prison, a cough could turn into tuberculosis (TB), and TB could turn into death, and nobody outside the walls would ever hear about it.
Incarcerated people at the national penitentiary in Port-au-Prince were dying of untreated infections, seizures, abscesses, HIV. Nobody tracked it. Nobody planned for it. He brought what he could: blood pressure cuffs, soap, the occasional sink in a suitcase. Eventually, others joined him—nurses, students, friends who couldn’t unsee what they’d seen.
By 2005, the work had a name: Health through Walls. What started in Haiti grew to reach the Dominican Republic, Jamaica, Ghana, Tanzania, Malawi, Mozambique, and and a few others—quietly, steadily, and without much fanfare. The mission was simple: provide basic, sustainable healthcare to people in prisons who would otherwise go without it. But the simplicity of that mission belied just how hard it would be.
A main tenet of Health through Walls is to screen for and treat infectious diseases that are most prevalent in overcrowded prisons—TB being a key target. In places like Haiti, TB is often diagnosed the way it has been for decades: through symptom-based interviews conducted one-on-one. Although this is the standard, in overcrowded prisons, conducting individual interviews for symptoms is often crushed under the weight of strained logistics and staffing shortages. Then a shift began.
The first breakthrough was access to digital chest X-rays, a tool typically reserved for wealthier countries. Prisons in Haiti had long struggled to access traditional X-ray machines. These machines required a high degree of maintenance and space and also relied on a steady supply of X-ray film. John even tells a story about bringing X-ray films down to Haiti and convincing TSA not to scan them, as they would have been ruined. The first digital X-rays offered hope to overcome some of these barriers, but the early machines were not as portable or affordable as they are today. Through a grant, the penitentiary in Haiti was able to purchase a digital X-ray machine for $150,000 in 2017; however, the machine was destroyed in a prison riot within the first month of its arrival. Yet this setback—like others, including earthquakes, hurricanes, floods, coup d'états, armed violence, and fires—did not stop the efforts from advancing. Portable digital machines were soon after acquired and proved a more affordable and sustainable option.
Even with the introduction of portable systems, Health through Walls faced an immediate bottleneck: a radiologist to read the films. In Haiti, there was no one on-site. At one point, the workaround was a retired volunteer radiologist in Miami. He read up to 200 films a day and emailed the results back. The images would return the next day, get printed, inserted into health records, and passed along to locate the patient—who might, by then, be in a different cell block, transferred to another prison, or released entirely. The delay turned medicine into a scavenger hunt.
Then came the second breakthrough: artificial intelligence.
In 2022, Health through Walls began partnering with Qure.ai, an AI company that developed an algorithm to read chest X-rays and flag signs of active TB. The results were nearly instantaneous. A technician could take an image, upload it, and get a read within minutes—no radiologist needed, no 24-hour lag. For the first time, decisions about isolation, further testing, and treatment could be made in real time.
It was more than efficiency. It was a way to bend the arc of care toward immediacy and precision. With this technology, Health through Walls could launch full-scale, blitz-like screening efforts in facilities that had once been medically invisible. In 2022 alone, they screened over 5,000 incarcerated people in Haiti and diagnosed 500 cases of active TB. Roughly 80% of the positive AI readings were confirmed by traditional bacteriologic testing. The old machines hadn’t changed. But they now had a new soul.
What AI offered was not a replacement for clinical judgment, but a tool—a faster way to identify who needs help now. And in the context of prisons, where time and truth are both slippery, that speed can be the difference between catching a deadly infection and missing it entirely.
The work of Health through Walls has been truly trailblazing. John will figuratively parachute in to build programs from within a country, often without any known connections or familiarity with the local language. A core mission has always been to identify and treat deadly infectious diseases concentrated in prisons, such as tuberculosis. Health through Walls trained local nurses, developed medication protocols, and created paper and digital records where none existed before. They brought in lab equipment and helped ministries of health understand how to reach behind the bars. They brought medicine—but they also brought method. And they left it in the hands of the people who lived there, always with the idea of sustainability in mind.
Their presence helps to normalize healthcare in the most difficult environments. It also gives the incarcerated—often stripped of agency—a reason to trust again, or at least to hope in a system that was, almost by design, engineered to suppress those very ideals. This is the quiet and unglamorous work of persistence. Year after year, country by country, Health through Walls has been laying foundations for something larger than itself.
Unfortunately, the foundation of this work has begun to falter. With budgetary cuts to USAID, the organization has lost its largest source of support. Seventy-one staff members—more than 75% of the workforce—were laid off. Programs shrank overnight. Clinics held on the best they could. What they didn’t lose was their mission. In Mozambique, they’re still working. In Haiti, they’ve scaled back but haven’t disappeared. The people John trained are still there. The need hasn’t changed.
There’s a lesson in all of it: that the most enduring public health efforts aren’t propped up by grants alone, but by people—those willing to keep showing up even when the funding dries up and the spotlight moves on. Health through Walls has endured because its roots run deep: trust, mentorship, and a quiet refusal to give up on the unseen.
John May now lives in Miami to be closer to his work in the Caribbean, he also works full time as the Chief Medical Officer for Centurion Health. He and those beside him for the last 20 years have been quietly creating one of the most effective public health models for correctional medicine in the world—doing the kind of work most won’t, in places most overlook.
If any of this resonates with you, please understand there is a profound need—not just for funding or supplies—but for physicians, nurses, and the broader medical community to step into the spaces we’ve long ignored. Correctional healthcare remains one of the most underserved frontiers in medicine. The burden of disease behind bars is staggering—rates of tuberculosis, HIV, untreated mental illness, addiction—all concentrated in places structurally designed to disappear people. We need more hands. More humility. And more people willing to treat incarcerated patients with the same urgency and dignity afforded to anyone else.
The decades of work quietly led by Dr. John May, have shown what’s possible when the medical world stops looking away. What began with one physician making monthly trips on his own dime has grown into a living public health blueprint—one rooted in consistency, local knowledge, and long-term trust. It is proof that medicine doesn’t have to wait for perfect conditions or perfect systems. It just needs people willing to show up.
This is more than an appeal. It’s a reminder: that global health includes prisons, that dignity is not a limited resource, and that we cannot call ourselves committed to public health while carving out exceptions for the incarcerated. The scale of the problem is too big for one person, one program, or one country. It will take many of us—working in small, persistent ways—to shift what is possible.
Sometimes, the most transformative thing a clinician can do is to simply say: these lives matter too. And then show up like you mean it.