We tend to tell two basic stories about measles: first, that we had more or less eliminated the disease, and second, that it has resurfaced — more than 440,000 cases were reported worldwide between January and November — because of mindless anti-vaxxers who ignore science and celebrate libertarianism from the comfort of their Internet echo chambers.

Both of these narratives, however, are, at best, partial truths. While anti-vaxxers are certainly part of the problem, increasing the numbers of people susceptible to the virus, they are best understood as harmful scapegoats or dangerous distractions for public health experts. The real threat of measles is rooted in the disconnect between what we know about the disease and actual public health practices.

Measles is probably the most contagious human disease we know: One person can contaminate 18 others, compared to just two in the case of the flu. This is why vaccination is so important. But it requires an extremely high rate of immunization, 95 percent, to protect “the herd.” And to be most effective, a vaccine must be given in two doses — raising the bar even higher for achieving this level of immunization.

Therein lies one problem: Many of those who do receive the vaccine don’t get both doses to make it work effectively. In fact, by the end of 2017, only 67 percent of children worldwide had received two doses, which means there are many children and adults who have been inadequately vaccinated. In Ukraine, for example, 44 percent of the 56,000 declared measles cases since 2017 are adults improperly vaccinated in the 1970s and 1980s. Ukraine’s conflict with Russia since 2014 has not helped the situation; public health is in shambles, and vaccines are in short supply. This combination of the recently non-vaccinated and the older inadequately immunized population created a massive outbreak.

Ukraine’s situation may be unique, but while the overall number of measles cases in the world has plummeted since the 1980s, Germany, France, New Zealand and other countries have faced outbreaks since 2000, and measles remains one of the main child killers in developing countries. Why does this preventable disease still exist? Because countries have not invested in the resources and infrastructure to turn medical knowledge of how to eliminate the disease into a reality.

In 1954, the American virologist John F. Enders isolated the responsible virus and began to search for a measles vaccine. Measles had certain biological traits that made finding a vaccine easier: the virus does not mutate, and human beings are its only hosts. Enders’s chief concern was the high cost associated with long hospital stays linked to complications, not the death rate of the disease itself. The disease was also forcing American women, who were increasingly entering the workforce, to stay home for days with contagious children.

In the early years of the Cold War, the eradication of measles came to be seen as a worthy scientific endeavor and the measles vaccine as an efficient productivity booster. In 1962, as several measles vaccines were still in pre-marketing clinical trials, David J. Sencer, H. Bruce Dull and Alexander D. Langmuir of the Communicable Disease Center (now called the Centers for Disease Control and Prevention) stated that measles would be eradicated within the United States as soon as 1967. Vaccination campaigns began in 1963, but this goal proved unrealistic. That was partly due to the Nixon administration ending federal support for measles vaccination programs in 1969, and with the priority given by public health authorities to the promotion of a new rubella vaccination program, measles cases actually tripled between 1968 and 1971, and vaccine coverage stagnated at 63 percent.

In October 1978, Health, Education and Welfare Secretary Joseph Califano again committed the United States to eliminate “indigenous measles,” taking an important step toward a global eradication process. But as it had a decade earlier, reality lagged behind this benchmark; budget allocations for vaccination clinics were not always sufficient, particularly during Republican administrations, and for many Americans, the vaccine, mandatory for school in all states by 1980, was never provided free of charge despite its high cost.

In other countries, measles elimination and global eradication were simply not a public health priority. In the United Kingdom, the emphasis was on vaccinations of vulnerable groups until the mid-1980s. The World Health Organization (WHO) also resisted the CDC’s demand that the eradication of measles be given priority, doubting it could be achieved. Moreover, adequate vaccine supply and distribution have been routinely back-burnered as MMR (for measles, mumps, rubella) vaccines costs have increased: Two doses of Merck M-M-R in the late 1980s cost about four times what a measles vaccine did in the mid-1970s. It was not until 2000 that measles eradication even became a global goal. As pandemic threats and anxieties over reemerging infectious diseases and bioterrorism emerged, nongovernmental organizations came together to create the Measles Initiative to promote regional and global efforts to eradicate the disease.

The quest for eradication came at a cost, though. Countries chasing after the “eliminated” designation — which four European countries just lost and the United States has narrowly retained for the moment in the aftermath of the worst outbreak in 25 years — has increased stigmatization of minorities and migrants, often pointed to as the source of an outbreak. It also led to an unhealthy competition between developing countries to “win the game” (at the expense of sharing data about measles cases, for instance) rather than focusing on developing equitable and sustainable public health policies beyond targeted immunization policies and local measures to control outbreaks.

The shift toward “personal responsibility” in health promotion — “eat well, do not smoke, exercise regularly” — since the 1980s has further hampered these institutional challenges. As a result, mass education on the benefits of vaccination has disappeared, and public health authorities target individual behavior and personal accountability, rather than addressing structural and systemic contexts resulting in inadequate immunization and non-vaccinations.

The 2018-2019 outbreak in New York City was halted this summer by enforcing mandatory vaccination and opening more vaccination clinics, but the core issue of why measles spread — the absence of public prevention policies including steady access to a free, efficient vaccine that parents could trust because they were educated about its benefits — was not addressed.

Although measles was never completely “eliminated” as commentators often insist, the resurgences happening now are real. Cases are expanding due to the increasing density of cities and college campuses, amusement parks, and refugee camps, and by the expansion of international mobility.

Vaccination is one of the greatest medical achievements of modern civilization. But it is not a panacea, and anti-vaxxers, for all the damage they do, are not the only culprits in the revival of measles. All of us share in the historical amnesia of which we are accusing hesitant parents. We overlook links between social inequalities, malnutrition (a vitamin A deficiency may well have an impact on the seriousness of measles and on vaccine failures worldwide) and climate change (global warming leads to movements of groups in which density of population and malnutrition help propagate the infection).

In an age of accelerated mobility, ecological disruption and nationalist health politics, we might have to do more than develop a “better vaccine.”

Vaccines are neither “universal technical fixes” nor “simple solutions,” nor can they be reduced to hashtags (#VaccinesWork). Measles prevention is suffering as a (global) public health initiative. And the virus will continue to “come back” as long as we ignore the complex dimensions of this initiative and its complicated history.