Donald Ainslie Henderson, known as D.A. to his colleagues, was the Babe Ruth of public health. As a young epidemiologist with the Centers for Disease Control and Prevention, he cut his teeth during the 1957 H2N2 flu pandemic, which originated in Guizhou, China, and killed more than a million people before it could be curbed by a vaccine. In the nineteen-sixties and seventies, he led the effort to eradicate smallpox, finding clusters of people infected with the disease around the globe, tracing and isolating others who’d caught it, and providing vaccines to some of the world’s poorest children. It’s thanks to D.A. that we can now speak about smallpox in the past tense.
When we first met, in 1986, I was an intern at the Johns Hopkins Hospital, and D.A. was the dean of the School of Public Health, directly across the street. Like many epidemiologists of his vintage, he was a true-blue “vaccine man,” for whom the immunizations created in the course of the twentieth century were the pinnacle of modern medicine. For D.A., vaccines were the definitive answer to all contagious-disease questions. By contrast, I had begun my career at the dawn of the H.I.V. era. In the late nineteen-eighties, we had few medications, let alone a vaccine, with which to fight that virus. While we waited for science to progress, our only weapon was public health: we had to study the virus’s transmission, test for cases, reach out to those who were at risk, and educate them. At the beginning of the AIDS pandemic, some misguided politicians advocated quarantining the victims, and many doctors and nurses refused to treat them. Since then, I’ve devoted much of my working life to studying the social history of pandemics and the uses and misuses of quarantine.
D.A. and I saw each other often between 2006 and 2010, when, together with Martin Cetron, the director of the C.D.C.’s Division of Global Migration and Quarantine, I worked to help develop the concept now known as “flattening the curve”: using social distancing to decrease the peak burden on health-care systems and to buy time for scientists and doctors to respond. (Those now-familiar drawings of flattened curves, seen at White House briefings and elsewhere, were taken from one of Marty’s PowerPoint slides.) With the assistance of medical historians, epidemiologists, infectious-disease experts, and statisticians, we gathered more than twenty thousand documents from hundreds of archives across the country, focussing on how forty-three American cities responded to the 1918 flu pandemic. We looked, in particular, at how those cities employed isolation and quarantine, the banning of public gatherings, the closing of schools, and, in some cases, the shutting down of roads and railways. We found that those cities which used more than one intervention simultaneously, and which acted early and persisted for sustained periods, experienced significantly lower rates of death than those which didn’t. The fates of twenty-three “double-humped” cities were equally telling: having released the brakes too soon, they suffered a second spike in cases and in deaths, sometimes worse than the first. Many had to institute another round of social distancing—a thorny political task.
We presented our data for the first time on a bleak December day in 2006, at a hotel near the Atlanta airport, where the C.D.C. was holding a meeting on national pandemic preparedness. Several hundred people—state and local health officials, scholars, virologists, epidemiologists, and reporters—had flown in to attend; the George W. Bush Administration, concerned about a possible flu pandemic the next year, had asked us to come up with a plan. When I finished my talk, the first person to stand up and speak was the man we most feared. In a booming voice, one that carried the authority of a living legend, D.A. said that our carefully arrayed historical research was just that: history. Social distancing, he argued, would be hugely disruptive. It would ruin the economy. It would destroy jobs and hamstring education. Kids who were out of school would congregate in malls and spread the virus anyway. Better, he argued, to let the virus burn through the population while concentrating on an effective vaccine. Sitting down, he looked me in the eye and added, gruffly, “Cull the herd!”
As it turned out, D.A.’s dismissal didn’t mark the end of social distancing. During our current pandemic, most nations have embraced the idea. Because social distancing is a quiet form of civic action, and because its success results in fewer infections, it’s easy to underestimate its effects—and yet they have been formidable. Last month, a study published in Nature estimated that the social-distancing measures employed in the United States, China, South Korea, Italy, Iran, and France have prevented around five hundred and thirty million coronavirus infections—sixty million of them in the United States. (Currently, with distancing, the U.S. has reported around four and a half million confirmed cases; the real number is probably higher.) Another study, conducted at Columbia University, found that, if parts of this country had started distancing on March 1st—roughly two weeks before most Americans began to stay home—fifty-four thousand fewer people would have died. It’s difficult to say with certainty how many deaths flattening the curve has prevented, but it is likely in the millions. The global social-distancing effort has been “one of humanity’s greatest collective achievements,” Solomon Hsiang, the leader of the Nature study, said, in announcing the findings. “I don’t think any human endeavor has ever saved so many lives in such a short period of time.”
In March, when social-distancing policies were first enacted in the United States, they seemed like a bargain. The W.H.O. had calculated a case-fatality rate of 3.8 per cent for the novel coronavirus; by comparison, the rate of death during the 1918 flu pandemic was about 2.5 per cent. If those numbers weren’t enough to terrify you, there were images of intubated patients in I.C.U.s and of bodies in refrigerated trucks; in New York and elsewhere, hospitals were overloaded, ventilators were in short supply, and sirens echoed through the night. Fear is an excellent motivator. When our health officials asked us to stay home, we did so, despite the disruptions.
And yet the terrified unanimity of those early days didn’t last. It quickly became apparent that there would be great inequality in how the social-distancing measures played out. For some people, the Internet softened the blow: they could work and shop from home while staying connected and entertained. Others lost their jobs or, if they were essential workers, kept them while shouldering high shares of viral risk. Some businesses succeeded in accessing government loans while others were left to fail. Meanwhile, COVID-19 exposed preëxisting disparities in American health care. Poor and minority communities experienced disproportionate death. Other people, living in places where the viral surge had yet to arrive, found themselves making sacrifices without quite understanding why.
As the curve flattened, misconceptions took hold. Perhaps the biggest was that social distancing was a policy that would need to be enacted only once, for a brief period, after which the virus would be defeated and life would return to normal. With this fantasy in mind, politicians began to argue that the time had come to reopen. A number of factors—mounting economic distress, inevitable claustrophobia and fatigue, the President’s deranged tweets about “liberating” certain states, an explosion of justified protest against police brutality and racial injustice—combined to weaken the consensus around social distancing. Across the country, and despite a lack of testing-based data about how widely the virus had spread, bans on gatherings were lifted. We were tired of being shut in and shut down; we wanted to go back to the world we’d left behind in March. We told ourselves, erroneously, that our social-distancing efforts had defeated the virus.