Becoming a public-health expert means learning how to envision humanity’s worst-case scenarios for infectious disease. For decades, though, no one in the U.S. has had to consider the full danger of some of history’s most devastating pathogens. Widespread vaccination has eliminated several diseases—among them, measles, polio, and rubella—from the country, and kept more than a dozen others under control. But in the past few years, as childhood-vaccination rates have dipped nationwide, some of infectious disease’s ugliest hypotheticals have started to seem once again plausible.

The new Trump administration has only made the outlook more tenuous. Should Robert F. Kennedy Jr., one of the nation’s most prominent anti-vaccine activists, be confirmed as the next secretary of Health and Human Services, for instance, his actions could make a future in which diseases resurge in America that much more likely. His new position would grant him substantial power over the FDA and the CDC, and he is reportedly weighing plans—including one to axe a key vaccine advisory committee—that could prompt health-care providers to offer fewer shots to kids, and inspire states to repeal mandates for immunizations in schools. (Kennedy’s press team did not respond to a request for comment.)

Kennedy’s goal, as he has said, is to offer people more choice, and many Americans likely would still enthusiastically seek out vaccines. Most Americans support childhood vaccination and vaccine requirements for schools; a KFF poll released today found, though, that even in the past year the proportion of parents who say they skipped or delayed shots for their children has risen, to one in six. The more individuals who choose to eschew vaccination, the closer those decisions would bring society’s collective defenses to cracking. The most visceral effects might not be obvious right away. For some viruses and bacteria to break through, the country’s immunization rates may need to slip quite a bit. But for others, the gap between no outbreak and outbreak is uncomfortably small. The dozen experts I spoke with for this story were confident in their pessimism about how rapidly epidemics might begin.

[Read: How America’s fire wall against disease starts to fail]

Paul Offit, a pediatrician at Children’s Hospital of Philadelphia and co-inventor of one of the two rotavirus vaccines available in the U.S., needs only to look at his own family to see the potential consequences. His parents were born into the era of the deadly airway disease diphtheria; he himself had measles, mumps, rubella, and chickenpox, and risked contracting polio. Vaccination meant that his own kids didn’t have to deal with any of these diseases. But were immunization rates to fall too far, his children’s children very well could. Unlike past outbreaks, those future epidemics would sweep across a country that, having been free of these diseases for so long, is no longer equipped to fight them.

“Yeah,” Offit said when I asked him to paint a portrait of a less vaccinated United States. “Let’s go into the abyss.”

Should vaccination rates drop across the board, one of the first diseases to be resurrected would almost certainly be measles. Experts widely regard the viral illness, which spreads through the air, as the most infectious known pathogen. Before the measles vaccine became available in 1963, the virus struck an estimated 3 million to 4 million Americans each year, about 1,000 of whom would suffer serious swelling of the brain and roughly 400 to 500 of whom would die. Many survivors had permanent brain damage. Measles can also suppress the immune system for years, leaving people susceptible to other infections.

Vaccination was key to ridding the U.S. of measles, declared eliminated here in 2000. And very high rates of immunity—about 95 percent vaccine coverage, experts estimate—are necessary to keep the virus out. “Just a slight dip in that is enough to start spurring outbreaks,” Boghuma Kabisen Titanji, an infectious-disease physician at Emory University, told me. Which has been exactly the case. Measles outbreaks do still occur in American communities where vaccination rates are particularly low, and as more kids have missed their MMR shots in recent years, the virus has found those openings. The 16 measles outbreaks documented in the U.S. in 2024 made last year one of the country’s worst for measles since the turn of the millennium.

But for all measles’ speed, “I would place a bet on whooping cough being first,” Samuel Scarpino, an infectious-disease modeler at Northeastern University, told me. The bacterial disease can trigger months of coughing fits violent enough to fracture ribs. Its severest consequences include pneumonia, convulsions, and brain damage. Although slower to transmit than measles, it has never been eliminated from the U.S., so it’s poised for rampant spread. Chickenpox poses a similar problem. Although corralled by an effective vaccine in the 1990s, the highly contagious virus still percolates at low levels through the country. Plenty of today’s parents might still remember the itchy blisters it causes as a rite of passage, but the disease’s rarer complications can be as serious as sepsis, uncontrolled bleeding, and bacterial infections known as “flesh-eating disease.” And the disease is much more serious in older adults.

Those are only some of the diseases the U.S. could have to deal with. Kids who get all of the vaccines routinely recommended in childhood are protected against 16 diseases—each of which would have some probability of making a substantial comeback, should uptake keep faltering. Perhaps rubella would return, infecting pregnant women, whose children could be born blind or with heart defects. Maybe meningococcal disease, pneumococcal disease, or Haemophilus influenzae disease, each caused by bacteria commonly found in the airway, would skyrocket, and with them rates of meningitis and pneumonia. The typical ailments of childhood—day-care colds, strep throat, winter norovirus waves—would be joined by less familiar and often far more terrifying problems: the painful, swollen necks of mumps; the parching diarrhea of rotavirus; the convulsions of tetanus. For far too many of these illnesses, “the only protection we have,” Stanley Plotkin, a vaccine expert and one of the developers of the rubella vaccine, told me, “is a vaccine.”

Exactly how and when outbreaks of these various diseases could play out—if they do at all—is impossible to predict. Vaccination rates likely wouldn’t fall uniformly across geographies and demographics. They also wouldn’t decrease linearly, or even quickly. People might more readily refuse vaccines that were developed more recently and have been politicized (think HPV or COVID shots). And existing immunity could, for a time, still buffer against an infectious deluge, especially from pathogens that remain quite rare globally. Polio, for instance, would be harder than measles to reestablish in the United States: It was declared eliminated from the Americas in the 1990s, and remains endemic to only two countries. This could lead to a false impression that declining vaccination rates have little impact.

A drop in vaccination rates, after all, doesn’t guarantee an outbreak—a pathogen must first find a vulnerable population. This type of chance meeting could take years. Then again, infiltrations might not take long in a world interconnected by travel. The population of this country is also more susceptible to disease than it has been in past decades. Americans are, on average, older; obesity rates are at a historical high. The advent of organ transplants and cancer treatments has meant that a substantial sector of the population is immunocompromised; many other Americans are chronically ill. Some of these individuals don’t mount protective responses to vaccinations at all, which leaves them reliant on immunity in others to keep dangerous diseases at bay.

If various viruses and bacteria began to recirculate in earnest, the chance of falling ill would increase even for healthy, vaccinated adults. Vaccines don’t offer comprehensive or permanent protection, and the more pathogen around, the greater its chance of breaking through any one person’s defenses. Immunity against mumps and whooping cough is incomplete, and known to wane in the years after vaccination. And although immunity generated by the measles vaccine is generally thought to be quite durable, experts can’t say for certain how durable, Bill Hanage, an infectious-disease epidemiologist at Harvard’s School of Public Health, told me: The only true measure would be to watch the virus tear through a population that hasn’t dealt with it in decades.

Perhaps the most unsettling feature of a less vaccinated future, though, is how unprepared the U.S. is to confront a resurgence of pathogens. Most health-care providers in the country no longer have the practical knowledge to diagnose and treat diseases such as measles and polio, Kathryn Edwards, a pediatrician at Vanderbilt University, told me: They haven’t needed it. Many pediatricians have never even seen chickenpox outside of a textbook.

To catch up, health-care providers would need to familiarize themselves with signs and symptoms they may have seen only in old textbooks or in photographs. Hospitals would need to use diagnostic tests that haven’t been routine in years. Some of those tools might be woefully out of date, because pathogens have evolved; antibiotic resistance could also make certain bacterial infections more difficult to expunge than in decades prior. And some protocols may feel counterintuitive, Offit said: The ultra-contagiousness of measles could warrant kids with milder cases being kept out of health-care settings, and kids with Haemophilus influenzae might need to be transported to the hospital without an ambulance, to minimize the chances that the stress and cacophony would trigger a potentially lethal spasm.

[Read: Here’s how we know RFK Jr. is wrong about vaccines]

The learning curve would be steep, Titanji said, stymieing care for the sick. The pediatric workforce, already shrinking, might struggle to meet the onslaught, leaving kids—the most likely victims of future outbreaks—particularly susceptible, Sallie Permar, the chief pediatrician at NewYork–Presbyterian/Weill Cornell Medical Center, told me. If already overstretched health-care workers were further burdened, they’d be more likely to miss infections early on, making those cases more difficult to treat. And if epidemiologists had to keep tabs on more pathogens, they’d have less capacity to track any single infectious disease, making it easier for one to silently spread.

The larger outbreaks grow, the more difficult they are to contain. Eventually, measles could once again become endemic in the U.S. Polio could soon follow suit, imperiling the fight to eradicate the disease globally, Virginia Pitzer, an infectious-disease epidemiologist at Yale, told me. In a dire scenario—the deepest depths of the abyss—average lifespans in the U.S. could decline, as older people more often fall sick, and more children under 5 die. Rebottling many of these diseases would be a monumental task. Measles was brought to heel in the U.S. only by decades of near-comprehensive vaccination; re-eliminating it from the country would require the same. But the job this time would be different, and arguably harder—not merely coaxing people into accepting a new vaccine, but persuading them to take one that they’ve opted out of.

That future is by no means guaranteed—especially if Americans recall what is at stake. Many people in this country are too young to remember the cost these diseases exacted. But Edwards, who has been a pediatrician for 50 years, is not. As a young girl, she watched a childhood acquaintance be disabled by polio. She still vividly recalls patients she lost to meningitis decades ago. The later stages of her career have involved fewer spinal taps, fewer amputations. Because of vaccines, the job of caring for children, nowadays, simply involves far less death.

Demonstrators attack embassies of France, Belgium, Rwanda, Uganda, Kenya and the United States in Kinshasa.

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When the Panama Canal was unveiled by the United States in 1914, the roughly 50-mile-long waterway symbolized American power and technological advancement. But the glow of progress soon faded. Building the canal killed roughly 5,600 workers over a decade, and many historians think that the death toll was higher. “Beginning with Lyndon B. Johnson, American presidents of both parties understood the strategic necessity of handing the canal back,” my colleague Franklin Foer wrote last week. The 1964 anti-American riots in Panama revealed that “the anger over America’s presence would never subside.”

The 1977 U.S.-Panama treaties signed by President Jimmy Carter relinquished control of the canal to Panama and established the passageway’s neutrality. This move sowed discord in the Republican Party, the rumblings of which are most clearly felt in President Donald Trump’s recent pledge to retake the canal. I spoke with Franklin about why Trump is fixated on this waterway, and what his preoccupation reveals about his vision for American expansionism.

Stephanie Bai: In Donald Trump’s inauguration speech, and even before he assumed office, he promised to retake the Panama Canal. Is this an issue that Americans care about?

Franklin Foer: Until Trump started talking about it, the Panama Canal hardly ranked on the list of the top 500 strategic threats to America. Best I can tell, there were some toll increases, and the Chinese have started to pay greater interest to the canal over time. But there’s zero national-security reason for the United States to deploy its prestige and military might to take back the canal. When it comes to his domestic audience, I think what Trump is betting on is a rising sense of nationalism that he can tap into. And I think by framing the canal as a lost fragment of the American empire and implying that it’s rightfully ours, he’s betting that it will be a piece of the broader “Make America great again” sentiment that he coasts on.

Stephanie: You wrote in your recent story that “reclaiming the Panama Canal is an old obsession of the American right.” Why is it important to that faction of the country?

Franklin: Many countries failed to build a canal connecting the Atlantic and Pacific Oceans, so America’s success was seen as a feat of engineering—at least, Americans viewed it that way for much of the 20th century. But its construction exacted an enormous human toll; thousands of workers died. And by the 1960s, most American presidents pretty clearly realized that the canal generated so much resentment toward the United States that keeping it didn’t make sense.

But you also had a large sector of the American right that felt like we were abandoning our empire. And so Ronald Reagan, when he ran for president in 1976, made reclaiming the Panama Canal one of his central slogans. The issue was something that the insurgent New Right movement, a rising force in American politics, exploited mercilessly in order to raise money and garner enthusiasm.

Stephanie: Trump’s grievances include his claim that the canal’s neutrality has been violated because it’s under the control of China.

Franklin: China likes to involve itself in the operation of infrastructure, and it has lots of global trading routes that it aims to control and exert influence over. There is a new Chinese presence in the canal, but that doesn’t mean that they’re about to take it over.

One of the things that’s ludicrously self-defeating about Trump’s strategy within the hemisphere is that he’s deliberately aggravating countries that could conceivably be thrown into the arms of China. So Panama may not want to enter into any sort of alliance with the Chinese, but because Trump is threatening military action against it, the country may decide that aligning more closely with China is in its interest.

Stephanie: In response to Trump’s inauguration speech, Panama President José Raúl Mulino said that “the canal is and will remain Panama’s.” As you noted, Trump has already floated the idea of using military force to retake the canal. Do you think this could actually come to pass?

Franklin: I think Trump is testing limits to see what he can get. I would be surprised if he was asking the Pentagon to draw up plans right now to retake the Panama Canal. But the problem is: Once he goes down this road of threatening to use military force to take something back, what happens when Panama doesn’t give it back? I don’t think there’s an extremely high chance that we will go to war to take back the canal. But I think there’s at least some possibility that we’re going down that road.

Stephanie: American expansionism seems to be top of mind for Trump. He talked about his “manifest destiny” vision in his inauguration speech, and he has repeatedly spoken about annexing Greenland and Canada in addition to taking back the Panama Canal.

Franklin: The fact that he’s using the term manifest destiny, which is a callback to American expansion in the West in the 1840s and 1850s, shows that this is not a departure from American history but a return to the American history of imperialism.

This is a big shift in the way that America now thinks of its role in the world. I think for Trump, who is a real-estate guy, acquiring real estate is a token of his greatness. He looks at Vladimir Putin and sees the way in which Putin has projected his power to expand his territory with Ukraine and thinks, Well, that’s what powerful leaders and powerful nations do. And here he is starting to explore that possibility himself.

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Trump is expected to sign executive orders that would ban transgender people from the military, reinstate troops who were discharged for refusing to get the COVID-19 vaccine, and remove the military’s DEI programs. Colombia reached an agreement to accept the flights of deported migrants from the U.S. after Trump made threats that included steep tariffs and a travel ban on Colombian citizens. U.S. markets fell today after the Chinese AI company DeepSeek’s latest cutting-edge chatbot app shot up in popularity over the weekend.

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The Worst Page on the Internet

By Yair Rosenberg

The worst page on the internet begins innocently enough. A small button beckons the user to “Click me.” When they do, the game commences. The player’s score, or “stimulation,” appears in the middle of the screen, and goes up with every subsequent click. These points can then be used to buy new features for the page—a CNN-style news ticker with questionable headlines (“Child Star Steals Hearts, Faces Prison”), a Gmail inbox, a true-crime podcast that plays in the background, a day-trading platform, and more. Engaging with these items—checking your email, answering a Duolingo trivia question, buying and selling stocks—earns the player more points to unlock even more features.

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