Amanda Ripley is a contributing writer at the Atlantic and the author of “The Unthinkable: Who Survives When Disaster Strikes — and Why.”

One summer evening in 1894, in the midst of a smallpox outbreak, health officials headed to a Milwaukee home to take a sick 2-year-old to the hospital. They were met by several thousand neighbors surging into the streets, clutching knives, bricks and bats. “I will not allow my child to be taken to the hospital!” the mother screamed. Police drew their guns. The ambulance left, empty.

For a month, riots crackled through the poorest parts of Milwaukee, spreading smallpox among the most vulnerable. In the end, 1,079 people got sick, and 244 died. Most heartbreaking was the timing: This catastrophe happened years after a smallpox vaccine had become available. So much suffering could have been prevented had officials better understood human behavior.

Over the years, we’ve learned a lot about how people behave in public crises. The vast majority will cooperate with public directives and make significant sacrifices, under certain conditions.

What happened in Milwaukee? That summer, the health commissioner had allowed families in middle- and upper-class areas of the city to self-quarantine in their homes when sick. But in the more crowded German and Polish immigrant neighborhoods, the city had forcibly removed and hospitalized the ill, citing unsanitary conditions.

This double standard violated the most important condition for public cooperation in crises: basic fairness. “Unless the public is convinced it is receiving fair treatment, equitably applied, it will resist public health policy,” medical historian Judith W. Leavitt wrote about Milwaukee’s outbreak in the journal Biosecurity and Bioterrorism. As word of this double standard spread, immigrant families hid sick children when officials came to the door. The mother who would not allow her toddler to be taken away that night? She’d already had one child die in the hospital, and she had no reason to trust authorities with another.

Today, the only way to slow the spread of the coronavirus is to win cooperation from the public. We know from history that this can be done. But only if any directives given to the public are understandable and fair and allow people some amount of autonomy. Until a vaccine is found, these three principles — clarity, fairness and autonomy — remain our best empirically proven approach.

So far, the United States is failing on two of three. The fairness principle was violated when wealthy or famous Americans got access to testing before other, sicker Americans. And it continues to be violated.

Our greatest failure has been a lack of clarity. The warnings have not been nearly as understandable as they could be. Promising that everyone could access testing when it was simply not true undermined any future request President Trump might make of the public. But he is not the only one failing. Public health officials, politicians and journalists are saying inconsistent, inaccurate things using misleading words.

“This might be the largest public information mess I’ve ever witnessed,” says Dennis Mileti, professor emeritus at the University of Colorado, who has studied and designed public warnings for 45 years. “It just breaks my heart. We know how to do emergency planning better than anyone on Earth and it’s not there.”

Words matter. The phrase “social distancing” is inaccurate. “Physical distancing” is much more accurate. Asking people to stay home except to go to the grocery store, do essential jobs or exercise, as has happened in California and other places, is not a “lockdown." That’s like calling a traffic light a military blockade. It makes it sound as though the government is forcing us to stay inside, which means it might be less effective, ironically. Americans will do remarkable things when asked, but they don’t like to be forced.

Autonomy is key. In 1947, New York City experienced a smallpox outbreak that started out like the Milwaukee tragedy. The vast majority of New Yorkers were not vaccinated and had no immunity to the disease, which was introduced by a visitor from out of state. But everything after that went differently.

The health commissioner had the authority to forcibly hospitalize sick people, but he didn’t use it. Instead, he held daily news conferences and delivered clear, consistent, transparent messages to the public. The city handed out buttons, empowering people to “Be safe. Be sure. Get vaccinated.” They offered free vaccinations in every public and parochial school around the city. The mayor and even President Harry S. Truman got publicly vaccinated themselves.

In one month, more than 6 million New Yorkers got vaccinated — voluntarily. People waited hours for their turn. The city had braced itself for a possible 4,900 deaths, based on previous smallpox outbreaks; in the end, there were just 12 cases — and two deaths.

“What New York teaches us is, you inform and involve people in crafting solutions to the threat,” says medical anthropologist Monica Schoch-Spana at the Johns Hopkins Center for Health Security. “You respect the public’s autonomy, and you give them the information they need.”

Last week, we got a glimpse of what this might look like at the national level — not in the United States but in Germany: “I firmly believe we will manage this task if really all citizens see it as their task,” Chancellor Angela Merkel said in a surprisingly honest address to the German people. “Nobody is expendable. Everybody counts. It requires effort by all of us. This is what an epidemic shows us.”

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