In the early 1960s, American childhood was not what it is today. Many children spent hours playing unsupervised in the streets; they rode around in cars without seat belts, then came home to frozen dinners, served in front of TVs blaring cigarette ads. And at some point, they’d almost certainly get measles.
The illness—caused by a virus that is estimated to infect roughly 90 percent of the unimmunized people it comes into contact with—is widely considered one of the fastest-spreading diseases to ever plague humankind. Before the debut of the first measles vaccine, virtually every child in the country could expect to contract it by the time they finished middle school, making it an experience nearly as universal as entering a classroom, skinning a knee, or enduring puberty. “It was sort of a rite of passage,” Kathryn Edwards, a pediatrician and vaccine expert who retired from Vanderbilt University Medical Center in 2022, told me. Edwards, 77, is one of many people born before the first measles vaccine was licensed in 1963; she can vividly recall the pain, discomfort, and fear of having the disease.
The rise of measles vaccination changed all that, and by 2000, the disease had been declared eliminated from the United States, after public-health officials detected no transmission of the virus for a full year. But now measles outbreaks are igniting across the country in communities where vaccination rates have dropped—most recently in South Carolina, where officials have documented more than 130 infections, nearly all of them among unvaccinated people. The U.S. has now clocked nearly a year of continuous measles transmission; come January, the country will very likely lose the elimination status that took nearly four decades of vaccination to gain.
At this point, most Americans can still count on protection from the measles vaccines they received in childhood. And as long as the Trump administration does not completely remove access to those immunizations, the nation will not revert to anything close to its early-1960s state. Still, measles is so transmissible that even slight drops in protection can create space for the virus to infect widely. As outbreaks become common once again, Americans will have to confront just how insidious and difficult to control this virus can be.
One of measles’ most deceptive traits is that most cases, especially in healthy people, are relatively mild. On the one hand, that means that many survive the disease without serious lingering effects. Measles’ hallmarks include a few days of fever, followed by a migrating rash of flat red spots that disappear within the week; one of the disease’s most terrifying complications—brain swelling—occurs at a rate of just 0.1 percent. On the other hand, that means that many who survive the disease consider it of little consequence. In the mid-20th century, especially, measles was often shrugged off. Polio—which permanently paralyzed roughly one out of every 200 people it infected—“really scared the hell out of people,” Walter Orenstein, the associate director of the Emory Vaccine Center, told me. By comparison, measles registered to some as little more than an annoying, rashy blight. In 1960, the U.S. mortality rate was about one in 500,000, and even the surgeon general’s information specialists said the disease was “often welcomed as a guarantee of lifetime immunity.” During the first push for measles vaccination, in the ’60s, some people hesitated to get vaccinated, not because they feared harm from the vaccine, but because they thought, “What’s the big deal? I had measles; my kids can get it; fine,” Orenstein said. The country achieved widespread vaccination, in the end, after enforcing strict school mandates.
Measles was never inconsequential, though. Even a case that is initially “mild” can wipe out defenses that people have built up to other diseases—a kind of “immune amnesia” that can leave them more vulnerable to infection for months or years. Painful ear infections and prolonged bouts of diarrhea can accompany close to a tenth of measles cases. Some 5 percent of infections result in pneumonia that can eventually turn fatal; rarely, measles can also leave children deaf or blind. The disease also tends to hit undernourished, immunocompromised, and pregnant people particularly hard, and many of the severest cases tend to occur in the youngest children. This year, the U.S. has clocked more than 1,900 measles infections—the most the country has documented since 1992—and 11 percent have resulted in hospitalizations. Three people have died, two of them children.
William Moss, a measles researcher at Johns Hopkins University, remembers witnessing the measles resurgence that tore through New York in 1990 and 1991 and watching some of the children hit by the outbreak struggling to breathe as they battled pneumonia. Several of those children died. Measles is “not a harmless disease,” Orenstein told me. “But the vast majority of people did not see that.” That was part of the irony of measles’ omnipresence: Amid a sea of less severe cases, serious suffering and death could pass by unnoticed. And over the decades, as vaccination reduced the number of measles cases that people saw, the occurrence of those rare but terrible outcomes has decreased further still.
In this way, measles vaccination—already considered by some as not worth the effort—has become a victim of its own success, Stanley Plotkin, a virologist and one of the developers of a rubella vaccine, told me: By corralling the disease’s dangers, it has reduced the incentive to protect against them. The measles vaccine is one of the most effective vaccines ever developed, capable of providing decades of immunity at a rate of about 97 percent. Vaccination has been essential to eliminating measles from this country, and dozens of others around the world. But the vaccine can only manage that when a population matches that effectiveness with a nearly equally high level of immunization buy-in, Boghuma Kabisen Titanji, an infectious-disease physician at Emory University, told me. Researchers estimate that, to stave off measles outbreaks, about 92 to 94 percent of people in a community must be immune to the virus. Dip even slightly below that threshold, and the virus, once introduced, can and will gain a foothold.
Measles elimination, then, is a particularly tenuous state, Moss said—potentially, the most unstable elimination status for an infectious disease that a country can have. The virus is so fast-moving that any cracks in our defenses create an opening for it to slip through. As a discipline, public health operates at its best when it can get near-universal buy-in for preventing bad outcomes. But measles’ defining traits can run directly counter to that impulse: People are far less likely to opt into interventions when the problems they need to avoid are rare and tend to concentrate in society’s more vulnerable sectors.
In the U.S., community leaders managed to gain and keep that buy-in for a long time. By the time Edwards was completing her medical training in the 1970s, “we didn’t see measles very much,” she said. She assumed that downward trajectory would continue. To see that trend now reverse, she told me, feels like the negation of decades of hard work—so much so that she’s started to wonder what the point of her entire career has been. Instead of celebrating a 26th year of measles elimination, the U.S. is staring down the impending costs of resurgence.
As outbreaks become more routine again, even mild cases will exact a toll—emptying out classrooms, keeping parents and other caregivers from work, adding to the strain that wintertime viruses put on hospitals. A family that rushes an infected child to the hospital could inadvertently put an entire emergency room of people at risk; another that brushes off a fever might accidentally afflict an entire playgroup. Trying to track and contain a highly contagious virus—which requires interventions such as testing and rapid contact tracing—will tax public-health departments, too. One recent preprint estimated that across the many drains that the virus can put on medical systems, public-health responders, and economic productivity, an average measles outbreak can cost more than $750,000 to rein in.
Before measles becomes a common American experience again, it will creep into society’s unprotected crevices first. Children in unvaccinated pockets of the country are now developing measles’ telltale rash. Adults who were never vaccinated in their youth are falling ill, too, challenging health-care workers and epidemiologists to contend with a new reality of measles striking across the age spectrum. And as individuals who received their vaccines up to six decades ago reach old age, they’re becoming the unwitting subjects of a natural experiment: Researchers are nervously watching to see just how long their immunity might last. The worst outcomes will still be uncommon. But as measles returns to prominence, those numbers will inevitably rise, too.
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