The global-health organization Gavi ties the issue together, citing a storm of seemingly disparate factors: disinformation campaigns in Europe, a collapsing health system in Venezuela, and pockets of low immunization in Africa. In South Sudan, where hundreds of measles cases have been reported in recent months, efforts to vaccinate people after the country’s civil war appear to have been thwarted because of the difficulty of keeping vaccines cool—not because people are refusing them.

Though the United States’ own outbreaks are unrelated to one another in a physical sense, they are linked to a growing online disinformation movement. In a statement on Thursday, the CDC said the outbreak in New York is significant in part due to “misinformation in the communities about the safety of the measles/mumps/rubella vaccine. Some organizations are deliberately targeting these communities with inaccurate and misleading information about vaccines.”

Read: How misinfodemics spread disease

The overall effect is a single, global dilemma. There is no opting out. The death toll will go up or down; the choice is between doing what’s possible to contain the virus and enabling its spread. The ways media ecosystems have evolved and siloed people are familiar in political discourse, but they are less addressed in conversations about public health.

In a statement this week, U.S. Secretary of Health and Human Services Alex Azar reiterated a tactic that has proven ineffective at reaching skeptical populations in recent years: telling them what to do. “Vaccines are a safe, highly effective public-health solution that can prevent this disease,” he said. “The measles vaccines are among the most extensively studied medical products we have, and their safety has been firmly established over many years in some of the largest vaccine studies ever undertaken.”

Earlier this month, CNN asked 10 current and former liaison members of the CDC’s Advisory Committee on Immunization Practices about the agency’s plans for countering anti-vaccination disinformation online. The response of the senior director of infection control at the Children’s Minnesota Hospital, Patricia Stinchfield, was emblematic: “I feel like on social media, the anti-vaxxers are very sophisticated and active and way ahead of us.” Another official, who declined an interview with CNN, issued a statement that included: “It is critical that parents and anyone seeking information about vaccines have access to credible information.”

Research suggests that the reason informed people fall into conspiracy-theory mind-sets often has less to do with a lack of information than with social and emotional alignment. Facts are necessary, but not at all sufficient. Websites and YouTube videos where a federal employee in a suit states various statistics are unlikely to be effective against targeted disinformation campaigns that only need to plant the seed of doubt in the mind of people already skeptical of the medical establishment. The work of global inoculation requires first rebuilding a social contract, which means meeting people on the platforms where they now get their information, in the ways they now consume it.