The Bear and The Microbe

A grizzly bear weighs more than 1,000 pounds, can run faster than a racehorse, and possesses claws and teeth that make human beings look laughably ill-equipped for survival. Yet in The Edge, it is not the bear that ultimately demonstrates superiority. It is the human mind.

This movie, made decades ago, is something that I keep coming back to. I am drawn to this movie because of its theme — the edge that humans have over other species. The edge that enables us to thrive in a natural world that is often hostile. That edge is not an opposable thumb but our specific consciousness which houses the faculty of reason. It is reason that allows humans to shape the world in a manner that is conducive to human survival, beating back lions, tigers, wolves, floods, hurricanes, and — critically — infectious diseases. It is also the case that the knowledge discovered by one human mind can be acquired by another, creating a web of information flow that serves to promote human life beyond the temporal and spatial bounds it was discovered in.

The Edge is fundamentally about thinking and using one’s mind to solve problems related to survival. In the film, a group of men are stranded in the wilderness. However, it is not the physically strongest human that flourishes but the one most committed to the use of reason. As they square off against the elements and the superior physical prowess of bears, it is the mind that triumphs.  This is not surprising. As the philosopher Ayn Rand identified, and the film dramatizes, reason is man’s means of survival.

Darwin understood that humanity’s distinctive adaptation was not speed, strength, claws, or teeth. It was intelligence. Reason, he wrote, stands “at the summit” of mankind’s mental faculties. Humans survive not by adapting themselves to every environment, but by adapting the environment to themselves.

As such, it is the human capacity to reason that stands as the ultimate resource to call upon for survival issues.

These survival issues most definitely extend beyond bears. The bear in The Edge is simply a stand-in for nature’s threats. For most of human history, those threats included yellow fever, smallpox, cholera, plague, tuberculosis, and influenza and only in recent generations have some humans secured freedom from the disruption, death, and despair that characterizes infectious disease outbreaks.

The story of infectious disease is the story of reason applied to nature. Smallpox did not disappear because nature became kinder. Cholera was not defeated because rivers became cleaner. Yellow fever did not retreat because mosquitoes became less dangerous.

Human beings identified causes, discovered mechanisms, tested hypotheses, and transformed knowledge into action. Every vaccine, antibiotic, sanitation system, intensive care unit, and genomic surveillance network is reason made tangible.

Left to her own devices, Mother Nature would kill us. Survival rdepends on the ability to think. It is not automatic; it is an achievement. The edge that separates humanity from the bear, the mosquito, and the microbe is ultimately the same edge dramatized in the film: the reasoning mind.

If You Want to Be a Real Darwinist, You Vaccinate

“There is reason to believe that vaccination has preserved thousands” — Charles Darwin

An argument that impacted how I think about vaccination happened not in a clinic or a hospital, but on a boat near the Galápagos Islands, where a naturalist guide told me that humans shouldn't try to modify their lives in ways that interfere with natural selection.

He meant it as wisdom. He was wrong, and Darwin himself would have told him so.

Darwin's most important sentence could be one you don’t know

Everyone knows Darwin for On the Origin of Species, published in 1859. But the book that reveals what he actually thought about human beings is The Descent of Man, published in 1871, where he turned his lens from finches and tortoises onto humans.

A sentence that should be far more famous than it is comes from Chapter III: "Of all the faculties of the human mind, it will, I presume, be admitted that Reason stands at the summit."

That sentence isn’t just a philosophical aside. He wrote it as an evolutionary statement. By The Descent of Man, Darwin had worked out what distinguished humans from every other species: not our size, not our strength, not our speed, not even our immune systems — but our capacity to reason. To form abstractions. To look at a pattern and induce a principle. To look at a virus and build a countermeasure. Darwin’s view of reason is that it is the means of survival for humans.

For Darwin, reason is not separate from natural selection but is natural selection's crowning project.

The Galápagos, of all places, is where this argument gets tested

I was standing in the place where Darwin assembled the observations that led him to his theory. Marine iguana, blue-footed Boobies, and the famous finches with their divergent beaks. And a guide — a naturalist, someone who had devoted his life to understanding this place — was telling me that when infectious disease shapes our species, we should let it.

I disagreed then, and I disagree now, on Darwin's own authority.

The guide's mistake was treating natural selection as something that happens to humans from the outside. But Darwin's argument was that reason itself is what natural selection built in us. When a virologist reads the genome of a novel coronavirus in January 2020 and a vaccine is in arms eleven months later, that isn't interference with Darwinian evolution. It's Darwinian evolution doing what it has been doing for millions of years: favoring the traits that help our species survive. Our trait is reason. Reasoning our way to vaccines. (Not by accident, Darwin’s view of reason was a topic I wrote a paper on in a favorite course I took in the 1990s as a post-baccalaureate student because I was so excited about the material: Jim Lennox’s Darwinism and its Critics at the University of Pittsburgh).

The anti-vaccine movement gets Darwin backwards

The "natural immunity is better" argument is an attempt at constructing a respectable-sounding voice of vaccine hesitancy. It has scientific adjacent clothing — it invokes evolution, selection pressure, immune memory and draws on real phenomenon. It sounds like Darwin.

It isn't. In fact, Darwin wrote: “There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox.” Darwin recognized vaccination as a triumph of reason. Jenner looked at milkmaids and cowpox lesions and induced a principle from scattered observations. He saw a pattern in nature and converted it into a technology that liberated humanity from smallpox. 

 The people who make this argument are, implicitly, asking you to treat nature as a norm-setter, something Darwin’s quote about vaccines stands in opposition to.  As if what nature does to us without our intervention is what should happen — those with “a weak constitution” succumbing to smallpox. This is the naturalistic fallacy dressed in evolutionary costume: the idea that because something is natural, it is good, or at least better than the alternative.

But Darwin didn't believe nature was a norm-setter. He described a blind, indifferent mechanism that favors whatever survives. He recognized that vaccination, a product of human reason, is a countervailing force that emanated from Edward Jenner’s faculty of reason.  Nature’s mechanism, devoid of human intervention, produces outcomes that no sane person would call a design goal: the Black Death killing a third of Europe; the 1918 influenza killing 50 to 100 million people; malaria, operating as a Darwinian selection pressure on the human genome for so long that it left permanent marks.

Which brings me to the honest face of natural immunity: it is a real phenomenon that comes at a cost.

Natural selection’s solution to malaria is a blood disorder

Of all the things I've written about infectious disease, the malaria-sickle cell story is the one that most concretely illustrates what natural selection, left to its own devices, actually produces.

It is often said that malaria has killed roughly half of all humans who ever lived. The Plasmodium parasites that cause it have been killing humans for so long, and in such numbers, that they became a selection pressure — they began to shape our genome.

The result: a mutation that, in carriers who inherit one copy, confers resistance to malaria. Natural selection preserved it because carriers survived long enough to reproduce. But inherit two copies of the mutation, and you have sickle cell anemia — a painful, debilitating, life-shortening blood disorder.

That is what natural immunity looks like when it's working as designed. Nature's answer to one of history's most lethal pathogens was to introduce blood diseases into the human population as a consolation prize. You can see the geographic overlap precisely: superimpose a map of where malaria has historically been endemic with a map of where sickle cell anemia (and the other malaria-influenced blood diseases G6PD deficiency, thalassemia, and hereditary spherocytosis) is prevalent, and the lines match almost perfectly. Natural selection did this. Over thousands of years of uncountable death.

Contrast this with what reason did to malaria: DDT eliminated it from most of the industrialized world within decades. Artemisinin-based therapies transformed treatment. Insecticide-treated bed nets keep sleeping humans safe. Vaccines decrease deaths. Modified mosquitoes will add even more. The tools built by conscious minds are doing in years what blind selection couldn't accomplish in millennia — and without the blood disorder as a byproduct. Human reason is also addressing sickle cell anemia, natural selection’s deadly byproduct, with bone marrow transplants and gene therapies.

The mRNA vaccine is what reason built

The mRNA vaccine platform is one of the clearest contemporary illustrations of this I know. For decades, scientists worked on the basic science of messenger RNA — how to stabilize it, how to deliver it, how to get cells to read it as an instruction and produce a protein. The key breakthrough on the delivery mechanism came in the 1990s. The key breakthrough on mRNA stability — a modification to the nucleoside that makes up the molecule — came from Katalin Karikó and Drew Weissman, a discovery that eventually earned the 2023 Nobel Prize in Medicine (and a Time Magazine cover that adorns my wall). None of this was done in anticipation of a specific pandemic. It was basic science, driven by curiosity and the slow accumulation of knowledge.

When SARS-CoV-2 arrived, its genome was sequenced and published in January 2020, and within 11 months, a vaccine built on that entire accumulated foundation was authorized and in arms. The speed looked miraculous. It wasn't. It was what happens when reason suddenly has a problem needing a solution at maximum urgency.

I have been calling vaccines "liberation technology" for years. When humans refuse to accept hostile nature's terms, they create the means to master these problems, winning freedom for themselves from being helpless against nature’s machinations. 

The deeper point is Darwinian: we aren't refusing nature's terms. We are executing nature's terms. 

Nature built a species capable of this: us. When we use that capability, we aren't defying the process that made us. We are the process that made us.

What my Galápagos guide got wrong

The guide on that boat had a philosophy that sounds like reverence for nature but is actually a form of self-abnegation. He was asking members of the most cognitively sophisticated species in the history of the planet to suppress the faculty that makes them what they are, out of deference to a blind mechanism that, left to itself, produces sickle cell anemia and the Black Death.

Darwin would have found this baffling. The man who spent his life documenting the adaptive genius of natural selection understood that what it had built in us — above all else — was reason.

The anti-vaccine movement, in all its varieties, makes the same error as my guide. It mistakes nature for a moral authority. It treats "natural" as a synonym for "correct." It advocates letting disease do what it would have done before we had the capacity to stop it, on the theory that this is somehow more authentic to who we are.

But nothing is more authentic to who we are than thinking our way to a solution.

The real Darwinists vaccinate

There is a false version of Darwinism that concludes vaccines are interference.

Darwin's version —reason standing at the summit — concludes something quite different. It concludes that the species capable of reasoning its way out of the jaws of infectious disease is doing exactly what natural selection shaped it to do. That is the mRNA vaccine, developed from a genome sequence in under a year. It stands as one of evolution's most recent and most impressive outputs.

We have had 10,000 generations of humans. Only the last four have lived in a world where we can reliably master some infectious diseases. The tools that made that possible — vaccines, antimicrobials, diagnostics, sanitation — are the products of the one trait Darwin identified as the summit of what natural selection can build.

If you want to honor Darwin, don't retreat to nature's indifference. Use your mind. That's what Darwin said it was for.

Vaccinate. 

Civilization’s Vampire Slayers

I have always been fascinated by the macabre, the occult, and the mysterious. Maybe it was a form of psychological reactance as a Catholic school student from kindergarten to 8th grade? Vampires were always a favorite and I thought it was cool that I lived in Pennsylvania and there was a place with the same suffix called Transylvania that was part of vampire lore. I even climbed the 1400+ stairs of Poenari Castle in the Romanian Carpathian Mountains to see the ruins of what was, I imagine, an impenetrable fortress of Vlad the Impaler, Bram Stoker’s historical Dracula.

Long before microbes were understood, people often explained epidemics through monsters. Vampires, witches, curses, and demons were attempts to impose agency on otherwise mysterious illness.

The vampire is often associated with disease causing rats and bats. His Transylvanian soil required for travel can be “sterilized” with Eucharist wafers to force him to flee back to his home. Vampirism was also thought to be related to tuberculosis as individuals consumed by the disease were thought to be being consumed by vampires rising from coffins.

I’ve written about how I liken being an infectious disease physician to being akin to a Ghostbuster, Indiana Jones, a Man in Black, and an exorcist but it is also like being a vampire slayer.

When it comes to vampire slayers, there is only Buffy — and Faith. I absolutely relished the Romanticism of the movie Buffy the Vampire Slayer but the series starring Sarah Michelle Gellar was really where the parallel with infectious disease was most apparent. Not only did Buffy and her clan have to battle myriad monsters (i.e., different pathogens), they consulted librarian Giles to research what they were up against (i.e., made diagnoses). Different countermeasures were directed at different creatures, just like in infectious disease.

There’s another really poignant scene I’ve been thinking about from that series that concretizes an important point about infectious disease control. When infectious disease control systems are working, they’re invisible. Unbeknownst to the individuals being protected, it is keeping people safe. The “it” here are the epidemiologists, the public health department personnel, the microbiologists, and the infectious disease physicians. To paraphrase Men in Black: they go to places you need not go, see things you need not see.  Rarely do they get thanks — infectious disease is one of the least financially lucrative areas of medicine.

This invisibility can also work against them as people are unaware of what is keeping the demons at bay, beating the devil back; the victories are largely invisible to the people they protect. When the outbreak doesn't happen, nobody cheers. When the pandemic doesn't spread past its index case because someone in a state health department noticed a cluster and made the right calls in the first seventy-two hours, nobody hands out awards. When vaccination programs keep measles from circulating in a school, the kids who didn't get encephalitis don't know they didn't get encephalitis. The Ghostbusters don't get a parade after defeating Gozer. They get their funding cut and their lab shut down by an EPA regulator.

Similarly, public health agencies are subject to neglect and cuts in funding, vaccines are devalued and smeared, infectious disease expertise is attacked. We see the results plainly with measles re-establishing endemicity, Ebola outbreaks festering for over a month unnoticed, and minimal situational awareness of avian influenza.

Buffy has spent three years defending Sunnydale High from a parade of horrors — demons, zombies, hyena-possessed students, a principal who turned out to be a robot, and vampires. Nobody talks about it. Nobody acknowledges it. The monsters are fought mostly in the dark, largely alone, and when it's over, the next day proceeds as though none of it happened. The ordinary life of ordinary people continues precisely because someone was doing extraordinary work they couldn't see.

Then, at the prom, a student named Jonathan takes the microphone and reads from a card:

"We're not good friends. Most of us never found the time to get to know you. But that doesn't mean we haven't noticed you. We don't talk about it much, but it's no secret that Sunnydale High isn't really like other high schools. A lot of weird stuff happens here. But whenever there was a problem, or something creepy happened, you seemed to show up and stop it. Most of the people here have been saved by you, or helped by you, at one time or another. We're proud to say that the Class of '99 has the lowest mortality rate of any graduating class in Sunnydale history."

Buffy is named “class protector”.

That’s the closest most people ever get to understanding what public health actually does — not a press briefing, not a policy paper, but a kid at a microphone trying to put words to something he can’t quite name.

That's how infectious disease preparedness and public health work.

The people who keep pathogens from killing you are working with the same energy whether you're paying attention or not.

Prior to this scene Buffy states that she just wants her classmates to have a normal prom, no matter how many people she has to kill.

That’s what the entire infectious disease apparatus is doing as well — trying to give everyone a normal life where they can pursue their values and achieve, free from the dread and disruption of infectious disease.

That is the mission of infectious disease control.

Not to dominate people’s lives. Not to control society. Not to make itself visible.

The goal is to make normal life possible.

But civilization is full of unseen guardians.

Some carry stakes. Some carry microscopes.

Class protector — civilization protector —infectious disease physician

Guardians of Human Flourishing: Infectious Disease Physicians

Pathogens are the obstacle. Human flourishing is the end.

Lately, I’ve been thinking deeply about what it means to be an infectious disease physician. Not the day-to-day work of managing drug-resistant bacteria, post-operative infections, or fevers in transplant patients, but the larger question beneath all of it. What exactly is the purpose of infectious disease medicine? What is its ultimate aim?

 First, every infectious disease physician stands as an intellectual descendent of a great lineage stretching back to Jenner, Pasteur, Koch, and Fleming and to D.A. Henderson. Those epoch-making minds were trying to solve real human problems that diminished the ability of humans to flourish. Their solutions — which include the germ theory of disease, vaccinology, and antibiotics—unequivocally augmented the length of human lifespans, diminished infant mortality, and facilitated much of modern medicine from chemotherapy to organ transplants to joint replacements.

As such, they advanced civilization. Every infectious disease physician, in their taming of even the most mundane of infections, is doing the same.

For much of human history, infectious diseases were a rate limiting check on human societies. A society might become too populous and invite crowd diseases such as measles, smallpox, and diphtheria to spread and cull the population. A society might become geographically tied to malarious areas or committed to cultural or gastronomical practices that increased interactions with specific animals, mosquitoes, and other vector species.

There have been 10,000 generations of humans and it is only the last 3-4 generations that humans have had some level of control and mastery of infectious diseases. What has transpired in that short period of time is arguably one of the most profound transformations in human history: a partial liberation from the microbial forces that shaped every preceding generation.

 In fact, it probably wasn’t actually dread as those humans were acclimatized to that baseline level of suffering, death, disruption, suboptimal lifespan, and atrocious  level of infant and childhood mortality that throttled their individual achievements and ability to reach the full potential of human life. That acclimatization still exists today in malaria endemic areas as Botswana’s President Boko recently argued).

Yet describing infectious disease as a constraint on human societies only raises a deeper question. Why does it matter that we have gained some measure of mastery over microbes? What is the purpose of that mastery? Is the goal of infectious disease

medicine simply the prevention of illness and death, or is it directed toward some higher end?

Aristotle, in the Nicomachean Ethics, argued that every craft, discipline, and human endeavor aims at some good, a telos or goal. Behind all of the intermediate or instrumental goals that people pursue lies an ultimate end: eudaimonia—human flourishing or living well.

If Aristotle is right then infectious disease medicine must also have a telos. That telos cannot simply be the eradication of pathogens any more than the purpose of architecture is the production of bricks. Pathogens are the obstacle. The end is something larger than being a pathogen hunter: preserving the conditions under which human beings and human societies can flourish.

An infectious disease physician, in my view, is a guardian of the conditions that allow civilization to flourish in the presence of pathogens. We are, to borrow the title of science writer Maryn McKenna’s excellent book on the CDC’s Epidemic Intelligence Service (EIS), “beating back the devil” in order to advance human civilization. During the COVID-19 pandemic, this role became explicit. Infectious disease physicians were called upon not merely to treat patients, but to help societies reopen schools, workplaces, hospitals, and public life itself, in effect being relied upon  to bring civilization back in the wake of the pandemic. 

There’s a scene in the movie Ghostbusters: Afterlife (I know, I try to tie this movie franchise to everything), where the teenage granddaughter of Dr. Egon Spengler, Phoebe Spengler, is asked to explain what she’s doing —  battling ghosts and investigating the paranormal—she replies simply “I am a scientist”. That scene encapsulates everything of what it is, to me, to be an infectious disease physician.

In that sense, I believe highest achievement of infectious disease medicine is not the conquest of microbes themselves, but the expansion of human freedom, civilization, and possibility through mastery of the microbial world. The late Jonathan Mann, the iconic former chief of the UNAIDS precursor agency at WHO, former state epidemiologist of New Mexico, and CDC leader once said what I evaluate as one of the greatest ways to describe the field of infectious disease. Writing about HIV/AIDS—but it applies to all infectious diseases—Dr. Mann said, “When the history of AIDS and the global response is written, our most precious contribution may well be that, at a time of plague, we did not flee, we did not hide, we did not separate ourselves.”

That, ultimately, is what infectious disease medicine is.

The Foreigner as Vector: America's Most Durable Public Health Myth

This week, a Kenyan court suspended a plan negotiated in secret between the Trump administration and the Kenyan government. The plan: build a 50-bed facility at Laikipia Air Base — roughly 200 kilometers north of Nairobi — to quarantine Americans exposed to Ebola in the DRC, rather than fly them home.

Kenya’s doctors’ union called the country a “dumping ground.” The Law Society of Kenya pointed out the obvious: Secretary of State Marco Rubio had just told a Cabinet meeting that the United States “cannot and will not allow any cases of Ebola to enter the United States.” If America, a first-world country, won’t accept that risk, why should Kenya?

Rubio’s line is telling. It is not an epidemiological or a medically-grounded statement. It is a political one — and it is the same political statement that has driven American infectious disease policy toward foreigners, immigrants, and “outsider” populations for decades, from both parties. It is almost always wrong. It is almost always damaging. And it never seems to go away.

The country that built 13 Ebola centers and then refused to use them

After the 2014 West Africa Ebola outbreak, the United States created something remarkable: a network of 13 specialized Ebola treatment centers with high-level biocontainment capacity. These are facilities designed specifically for this scenario — a highly lethal virus, limited natural contagiousness, spread through direct contact with blood and body fluids. They are the right tool for exactly this moment.

Instead of using them, the administration flew Dr. Peter Stafford — a 39-year-old American surgeon and medical missionary who was infected with Bundibugyo Ebola in DRC while treating patients — to Charité University Hospital in Berlin, Germany. His wife, Dr. Rebekah Stafford, and their four children were evacuated there too for monitoring. A second missionary doctor potentially exposed, Dr. Patrick LaRochelle, was quarantined at Bulovka Hospital in Prague, Czech Republic.

Two American physicians. Eight family members. Four countries. Zero American Ebola treatment centers used.

On May 18, the CDC (acting director Jay Bhattacharya signing the order) invoked Title 42 of the Public Health Service Act to bar non-citizens who had been in DRC, Uganda, or South Sudan from entering the United States. Four days later, the administration extended this authority to cover green card holders — lawful permanent residents — something the COVID-era Title 42 did not do, something none of Trump’s prior travel bans had done.

This is not a public health measure. It is the same ancient reflex, dressed in modern legal architecture.

The 1987 original sin

We have been here before.

In 1987, Senator Jesse Helms successfully added HIV to the list of “dangerous contagious diseases” that rendered foreign nationals inadmissible to the United States. The scientific logic was essentially nonexistent: HIV is not transmitted through casual contact, it does not spread through air or water, and the mode of transmission (sex, needles, blood products) is identical regardless of a person’s country of origin. HIV was, for 22 years, the only disease explicitly named by Congress in the Immigration and Nationality Act as grounds for denying someone entry to the United States.

The policy did not slow HIV transmission within the US. The epidemic spread anyway — through American communities, American hospitals, American blood banks. What the ban did do: it stigmatized an already-stigmatized population, deterred disclosure and testing, and sent the message that this disease was something that came from outside, brought in by foreign others, rather than something that spreads wherever the conditions that enable it exist.

It took until 2009 — George W. Bush signing the repeal authority and Obama’s HHS formally removing HIV from the inadmissibility list — to correct a policy that was wrong from the moment it was written. Twenty-two years of political theater, dressed as public health.

Biden punished South Africa for being honest

Administrations of both parties have played this game. In November 2021, South Africa’s scientists did exactly what the global health community asks countries to do: they identified a new, potentially significant COVID-19 variant, sequenced it rapidly, and reported it immediately to the WHO. Within days, President Biden banned travel from South Africa and seven neighboring countries.

As I said at the time: “They discovered a new variant, they sequenced it, they let the world know. Shouldn’t you be praising them? What is the incentive for the next country that identifies the next important variant if their reward is what President Biden did to South Africa?”

Omicron had already been detected in Europe, Canada, Australia, and the UK before the ban was even announced. The ban didn’t prevent Omicron from arriving in the US — it arrived almost immediately. What it did accomplish was economic punishment for scientific transparency, and the establishment of a precedent that will make every future South Africa think twice before being forthcoming.

The International Health Regulations — the internationally agreed framework for pandemic response — do not recognize travel bans as an effective public health tool. That has not stopped governments from reaching for them every single time, because they are politically useful. They look decisive. They tell voters you are doing something to keep them out.

The current Ebola response is an object lesson in what this reflex costs

The 2026 DRC Ebola outbreak is caused by the Bundibugyo species — a rare variant that standard diagnostic tests initially missed. That diagnostic delay is the main reason this outbreak, which should have been caught in the 20-to-30-case range, reached over 1,000 suspected cases before the world got a clear picture of what was happening. The delay was likely compounded by USAID dismantlement and disarray at the RFK-controlled CDC.

The travel ban does not address any of these problems. It does not improve diagnostic capacity in DRC. It does not send resources to the outbreak zone — in fact, it makes it harder to get resources and personnel in, because it chills the willingness of healthcare workers to volunteer when their ability to return home is uncertain. My colleague Alex Phelan made exactly this point in The Guardian. The cascading effect on air travel to the entire region means that even countries not named in the ban face reduced access.

Meanwhile, the US has 13 world-class Ebola treatment centers sitting empty. Dr. Stafford was sent to Germany not because Germany has better biocontainment infrastructure — it doesn’t — but because “no Ebola cases on US soil” is a political goal shorn from any grounding in medicine or epidemiology.

RFK Jr. blames immigrants. Here’s what he’s evading.

At a House Energy and Commerce Committee hearing on April 21, 2026, Health Secretary RFK Jr. — facing questions about the ongoing measles outbreaks spreading across multiple US states — said this: “It has nothing to do with me. If you’re worried about polio and tuberculosis, you should look at the immigration policies in this country. ‘Cause the place where it’s occurring are the places where the immigrants are going, because they’re not vaccinated.”

This statement requires a specific kind of rebuttal, because it is not just factually wrong — it is the inversion of what actually happened.

The current US measles outbreaks are concentrated among unvaccinated American citizens. The Texas outbreak started in a Mennonite community. South Carolina. Utah among fundamentalist Latter-day Saints. Florida. These are not immigrant communities — they are communities where American parents, influenced by the anti-vaccine movement, declined to vaccinate their children. The Mexico measles outbreak was seeded from Texas, not the other way around.

But there is a more specific and damning story here. The most striking example of vaccine hesitancy in an immigrant community in recent US history is the Minnesota Somali community — which suffered a major measles outbreak in 2017 and again in 2024. MMR vaccination rates among Somali children in Hennepin County had fallen from over 90% before 2008 to just 35.6% by 2014. That didn’t happen spontaneously. It happened because anti-vaccine groups — including Robert F. Kennedy Jr. and Andrew Wakefield — specifically targeted the Somali community with the false autism-MMR link. They held meetings in the community. They distributed materials. They exploited an existing, understandable anxiety about autism rates in the Somali-American population.

RFK Jr. and his allies created the conditions for vaccine hesitancy in a specific immigrant community. Then he stood in front of Congress and blamed immigrants for vaccine-preventable disease outbreaks.

The audacity of that position deserves to be stated directly and clearly, because it is not just hypocrisy — it is a continuation of the same tactic. Point at the outsider. Direct attention away from the actual cause. Repeat.

Title 42 for measles and TB: theater, not science

Earlier this year, the Trump administration considered reinvoking Title 42 — the pandemic-era border expulsion tool — based on claims that migrants were driving measles and tuberculosis into the United States. In March 2025, immigration law expert Agustina Vergara Cid and I analyzed this in STAT News, and the conclusion was straightforward: there is no epidemiological basis for this claim.

The bulk of US tuberculosis cases occur in legal migrants from Asian countries, diagnosed decades after arrival — not in asylum seekers from the southern border. The 2024 Chicago measles outbreak linked to Venezuelan migrants at a shelter was real — but the entire Western Hemisphere had re-achieved measles elimination status by that point, and the actual vulnerability driving US measles spread is domestic vaccination refusal, not importation from the south.

Our threshold for when an infectious disease border declaration could be legitimately contemplated is: the disease must be severely serious, must lack simple countermeasures, and must pose an epidemiologically significant importation risk. Measles has a vaccine. Tuberculosis can be diagnosed and treated to render the person non-infectious. Neither condition came close to meeting that threshold.

As we wrote in STAT: “Title 42 did nothing to blunt the impact of Covid-19 either — like the current scenario, it was a brazen attempt to use a crisis to achieve a separate policy goal.”

The CDC should not be a tool for immigration enforcement. When it is, it loses the credibility it needs to do its actual job. That is the real cost of this reflex.

What actually determines whether a disease spreads

Here is the thing about infectious disease that gets lost in every iteration of this debate: the pathogen does not check passports.

What determines whether a disease spreads in a population is not the nationality of the person who carries it into the country. It is whether the population they encounter is vulnerable to it and the transmission characteristics of the pathogen (Ebola is very constrained in that regard depending on blood and body fluid emanating from symptomatic patients). That vulnerability is a function of vaccination (when available) rates, surveillance capacity, and the ability to identify and contain cases quickly. A community with 95% MMR vaccination coverage is inhospitable to measles regardless of who crosses its border. A community where MMR rates have been driven to 35% — by a deliberate disinformation campaign — is a tinderbox waiting for a spark, regardless of whether the spark is an unvaccinated American returning from Europe or an unvaccinated immigrant from a country with low coverage.

What changes is not the science. What changes is which outbreak politicians need to deflect accountability for.

The cost we keep paying

Every time the “foreigner as vector” reflex runs its course, it costs something real.

The HIV ban didn’t stop HIV. It delayed testing, delayed treatment, and drove infected people away from the healthcare system for 22 years.

Biden’s Omicron ban didn’t stop Omicron. It established that countries which report new variants honestly will be economically punished — a precedent that makes the world less transparent about the next one.

The Title 42 Ebola ban and green-card expansion is a political tool, not an outbreak management tool. The ban does not make us safer. We have thirteen cutting-edge unrivaled centers that can handle and have handled Ebola if an American healthcare worker is infected. What the ban will do is make it harder to get responders into the outbreak zone, harder to sustain the international cooperation that containment requires, and easier for an outbreak growing at 1,000+ suspected cases to escape the region entirely.

The Kenya facility — courts permitting — would have quarantined Americans in a country with no Ebola infrastructure rather than use the infrastructure we spent a decade building, all to satisfy a political calculus that says “no Ebola shall touch US soil.”

And RFK Jr.’s immigrant-blaming, delivered under oath to Congress, will go into the record as the official government explanation for why measles is spreading in communities that his own movement depopulated of vaccine confidence.

These are not separate stories. They are expressions of the same idea: that the disease comes from them, not from us. That if we can just keep them out, we will be safe.

It is an idea with a perfect record of failure and a perfect record of political utility. That combination is why it keeps coming back.

The answer is not to restrict the movement of people. The answer is to build the population resilience — vaccination coverage, surveillance, treatment access — that makes any pathogen’s arrival an inconvenience rather than a catastrophe. We know how to do that. We have the tools to master this problem. We keep choosing not to use them, and then looking for someone to blame when the outbreak comes anyway.