Medical Examiner

The Anti-Vaxxer Movement Isn’t Really Growing

To insist it is distorts our view of public health.

A plane covered in red spots as if it has measles.
Photo illustration by Slate. Photo by Getty Images Plus.

On June 5, the number of measles cases in the U.S. this year passed 1,000, a milestone the country last reached in 1992. There’s little doubt, in most circles, about the source of this resurgence: It’s the anti-vaxxers’ fault. “Federal health officials attribute this year’s outbreak to U.S. parents who refuse to vaccinate their children,” noted Reuters in a recent update on the crisis.

That much seems self-evident: Measles spreads most readily through undervaccinated populations, so if the disease is newly spreading, then there must also be a major outbreak of vaccine refusal. The numbers tell a different story, though. As I’ve noted here in Slate, U.S. vaccination rates for measles aren’t really plummeting. In fact, they’ve been very stable over many years, at around 91 or 92 percent of the population. While it’s possible that local hotspots of refusal have gotten slightly bigger over time, or that more of these communities are cropping up, hard evidence in support of this idea has been rather modest.

Here’s a simpler, more convincing explanation for the sudden surge of measles: Much bigger outbreaks overseas have been spilling over to our shores. More than 66,000 cases have been registered in Europe since the start of the year, and there have been alarming flare-ups in parts of Africa and Asia, too. These crises have in turn set off the ones we’re seeing here. In May, the U.S. Centers for Disease Control and Prevention confirmed that the recent measles outbreaks affecting New York’s Orthodox Jewish communities and Russian speakers in Clark County, Washington, each started off with sickened travelers returning from Israel and Eastern Europe.

In other words, one doesn’t need to posit soaring rates of craziness within the U.S. to explain the growing public health disaster. It’s certainly true that pockets of vaccine refusal persist in this country, as they have for many years. If those pockets are now experiencing greater numbers of measles cases, it may be on account of dire trends in far-off places.

This global explanation only kicks the can a little farther down the road, however. Measles cases are spreading here because they’re spreading overseas—OK, fine. But why is measles spreading overseas?

Once again, the easy and most common explanation holds that anti-vaxxer propaganda is on the rise, not just here but everywhere—and that global vaccination rates are plummeting. Indeed, the World Health Organization made news this year by adding “vaccine hesitancy” to its list of the 10 principal threats to global health for 2019. The head of the Gavi Vaccine Alliance called misinformation about vaccines “a contagious disease” at a recent meeting of international health experts in Geneva. The latest issue of the British Medical Journal warns, “If vaccination rates continue their downward trajectory, measles may once again become endemic.”

Are vaccination rates really on a downward trajectory? Once again, the actual data complicate this narrative. Global immunizations against measles, like those in the U.S., are at or near an all-time high. Since the start of this century, the proportion of people around the world who have received at least one dose of the measles vaccine has increased by almost one-fifth. Meanwhile, the use of a second dose of the vaccine (which makes it more effective) has more than quadrupled on the global scale. In 2000, just 15 percent of people were getting both shots. Now, that number is up to 67 percent and still rising.

The salutary effects of all this work could not be more apparent. The global number of people who contract measles and the global number of people who die from it have each gone down by about 80 percent since 2000. As recently as 1980, more than 4 million cases of measles were reported every year. Despite massive population growth since then—an uptick of several billion people, worldwide—the annual number of measles cases has dropped to about one-fiftieth of what it used to be, to a few hundred thousand cases per year.

Given all this recent progress, the global measles crisis that’s underway seems somewhat paradoxical. Just look at what’s been going on in Europe. Two years ago, the region had its best year ever for immunization: An all-time record 90 percent of Europeans received two doses of the measles vaccine, and 95 percent got at least one dose. Then, almost immediately, measles swept across the continent, infecting more than 80,000 people in 2018 alone and killing 72. That rampage was at least three times as severe as any that had come in recent memory.

If more and more people are getting the vaccine, then how is the disease making such a comeback? Many different factors are at play. For one thing, measles epidemics tend to come in waves. When a supercontagious disease hits a population, it quickly spreads among the most susceptible, like a wildfire roaring through dry underbrush. Once the outbreak burns up all this ready fuel, it starts to dwindle. At that point, the people who got sick are now immune, and doubting parents may have become more inclined to vaccinate their kids. The population as a whole ends up more resistant to the illness than it was before.

This creates a feedback loop: As vaccination rates go up, measles cases start to disappear; then, as the illness gets rarer, resistance wanes among those who can’t or won’t get immunized. The next outbreak yields a surge in cases, which leads to more resistance overall and higher vaccination rates. Measles crises alternate with “interepidemic” periods, and the pattern only ends when vaccination programs reach about 95 percent of the population, the threshold for herd immunity.

Given current, insufficient levels of protection, periodic measles epidemics are more or less to be expected. That’s because immunization rates appear to have plateaued, in recent years, at around 85 percent. Communities of vaccine skeptics, found in many different countries, contribute to this problem—but they’re not the only cause. They may not even be the major cause. In the U.S., for example, the number of unvaccinated children has quadrupled since 2001—a stat that people  love to cite as evidence of a growing anti-vaxxer movement. But the CDC attributes that number to health care inequality, since kids without insurance or who live in rural areas appear to be at greatest risk.

The same applies to several of the countries where the latest measles crisis has been most devastating. Madagascar has registered more than 60,000 cases since January, but it’s not because people are refusing the vaccine; it’s because they can’t afford it. A second dose costs as much as a whole family might spend during a week, according to this Reuters report. Weather also plays a role: Research shows that vaccination rates fall off during the rainy season, when it’s harder for people to reach their nearest clinic. Meanwhile, a brand-new Wellcome survey of 140,000 people from around the world finds that 97 percent of Madagascans agree that vaccines are “important for children to have” (as compared with 87 percent of Americans).

Another recent hotspot has been Venezuela, with almost 6,000 cases since 2018. Again, this outbreak has far more to do with access than belief: The nation’s rather abrupt political and economic collapse has left the nation short of medication. Needless to say, there aren’t many signs that Venezuelan anti-vaxxer groups have been making gains on Facebook. Venezuelans are at the very top in terms of trust in vaccination, according to the Wellcome survey. Ninety-three percent agree that “vaccines are safe” while 99 percent agree that vaccines are important for children.

There are places where anti-vaccine sentiment has indeed been thriving, and where infections rage as a result. But one can often find specific, local causes for a rise in skepticism. In the Philippines, for example, some parents are responding to a dangerous and recent governmental blunder. A vaccine against dengue, given out in schools, turned out to carry mortal risks: The children who received it were at risk of developing something called plasma leakage syndrome. Experts guess that 10 to 20 Filipino schoolkids may have died as a result, and government officials are now facing criminal charges over the program.

Ukraine has been the source of most of Europe’s cases—and of the U.S.’s biggest outbreaks, too. The problem there has been linked, in part, to vaccine shortages from 2009 until 2016, and to the Ukrainians’ lingering skepticism of blanket immunizations that were in place under Soviet rule. They also had a major vaccine scare: In 2008, a teenager from Kramatorsk happened to die from a bacterial infection less than 24 hours after getting a measles and rubella shot at his school. Local news media quickly linked his death to an evil vaccination plot led by Ted Turner. The Ukrainian government made things worse by suspending its vaccination program while it investigated the teenager’s death, and even going so far as to detain its top public health official. The country’s faith in the MMR vaccine has not recovered since.

When we talk about the global measles problem, though, such particulars tend to disappear. Instead we talk ad nauseam about a burgeoning anti-vaccine movement here in the U.S., and across Europe, and all around the world. It’s often said, these days, that “the world is taking a step backwards” with waning faith in vaccination, and that anti-vaxxers have convinced “growing numbers of parents to shun the shots.” Or that the movement has metastasized on social media, or spread through the politics of populism, or otherwise turned into its own form of viral epidemic. A feature story on the anti-vaxxer movement in Jezebel, published Thursday, goes so far as to claim that this “growing” community “is remaking the world.” That’s plausible, I guess, but—once again—the solid, long-term numbers don’t support the idea.

Formal efforts to analyze and address the problem of vaccine refusal are still pretty new. The global health community first began to focus on the issue in the early 2000s, in the aftermath of a boycott of the polio vaccine (and associated outbreak) in Nigeria. The Vaccine Confidence Project, based at the London School of Hygiene and Tropical Medicine, was founded just a decade ago. A few years after that, international health authorities began requesting large-scale studies of the issue: In March 2012, the WHO’s advisory group on immunization established a Working Group on Vaccine Hesitancy; a year later, the U.S. Department of Health and Human Services directed its National Vaccine Advisory Committee to set up something similar. Each of these aimed to bring more rigor to the study of vaccine hesitancy and devise standard means by which it could be measured over time.

These efforts have started to pay off with more and better information, but data are still limited. In October, the Vaccine Confidence Project published the results of a massive survey on the state of vaccine confidence in the EU. The report compared its newest numbers from 2018 to those gathered from a 2015 survey. Vaccine-safety ratings went up by a statistically significant margin in eight out of the 20 countries included for analysis and stayed the same in another eight countries. Meanwhile, safety ratings dropped between 2015 and 2018 in just four countries: Finland, Sweden, Poland, and the Czech Republic. The countrywide upticks in confidence were also larger in magnitude, on average, than the countrywide declines. The biggest single increase in confidence, for example, was 16 percentage points, in France; while the biggest decrease, in Poland, was 7 percentage points.

There were some troubling signs in the report. For one thing, young people in Europe appear to be way more skeptical of vaccines than people over 65. Unless these overseas millennials change their minds as they get older, this doesn’t bode well for public health. But if we’re going only by the report’s measured trends in vaccine hesitancy across this brief interval—from 2015 and 2018—the news looks pretty good. If anything, vaccine skepticism (not to mention anti-vaxxer sentiment) may be shrinking, overall.

You won’t find that message in the news, however. Here’s how the New York Times described the same research in a recent story on the measles crisis overseas: “The anti-vaccine movement has been growing across Europe, most notably in Poland, according to a European Union report.” Reuters summed up the mixed results in this headline: “Vaccine Confidence Low in Europe, Raising Disease Outbreak Risk.”

Meanwhile, a BBC headline from just this week referred to distrust of vaccination as a “global crisis,” in reporting the results from that recent Wellcome survey. It’s true Wellcome found that only 79 percent of its respondents were willing to agree with the statement, “Vaccines are safe.” Then again, the same study found that the proportion of those who actively disagreed with the same statement was just 7 percent. (The rest had no opinion or refused to answer.) As for actual behavior, 92 percent of the people in the survey reported that their children had received at least one vaccine. These global averages match up very well with results from the United States. According to Wellcome, just 72 percent of Americans agree vaccines are safe, 11 percent disagree, and 93 percent say their children have been vaccinated.

The anti-vaxxer narrative persists despite these numbers; in fact, it even cites them. That’s because the story has been driven less by facts than reflex, and the instinct to assume that a sudden and resurgent spread of measles must be the result of something just as sudden and resurgent. A growing disregard for mainstream expertise, perhaps, or a viral spread of fringe ideas on social media, or a great succumbing to the power of fake news. This makes so much sense in principle—it’s so satisfying and outrageous—that the stats don’t really matter.

And so we’re left with news reports that claim, on the one hand, measles “vaccination rates have dropped,” while linking from that very phrase to data showing just the opposite. Or stories like New York magazine’s “Measles for the One Percent,” based around a shameless sleight of hand that makes you think the illness is a scourge of Luddite liberals whose suspicion of vaccines has exploded over the course of a single generation.

This all feels very true and clear, but it’s becoming a distraction. If we’re going to forestall the next round of measles epidemics, we’ll need to look at all the reasons why vaccination rates around the world have stalled out at less than 95 percent. Our obsession with the anti-vaxxers isn’t helping.