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.
The reality, of course, is that social distancing cannot cure or defeat COVID-19. It only allows us to hide from the virus while scientists do their work. The overwhelming majority of Americans—perhaps as many as three hundred million people—are still susceptible to infection. As they venture back into a reopened world in which the virus is still circulating, they are at risk. In the past few weeks, this simple reality has asserted itself. In states as varied as Texas, Arizona, Florida, and California, we have seen a steepening of the curve. Since June 15th, case counts in the United States have exploded from roughly twenty thousand new cases a day to more than sixty thousand. The U.S. now leads the world in the production of new coronavirus cases. The sheer number of new cases and deaths is staggering. Since May 28th, when the hundred-thousandth American died of COVID-19, sixty thousand more have been killed by the virus. The C.D.C. is now projecting that we will reach somewhere between a hundred and sixty-eight and a hundred and eighty-two thousand deaths by August 22nd. The harsh truth about our situation is clear: it isn’t over.
In 2006, when my colleagues and I first proposed the idea of flattening the curve, we hoped to draw up plans for the subsequent phases of a pandemic. We knew the basic idea: work would proceed on vaccines and treatments while testing, tracing, and isolation measures ramped up; meanwhile, the federal government would step in to keep households and businesses afloat. But, although the federal government developed a detailed pandemic plan, many stakeholders disagreed about when social distancing might become necessary, and about what should be done during an extended pandemic like the one we are experiencing now. In 2009 and 2013, when epidemiologists warned about the potential for a swine-flu pandemic and a widespread Ebola outbreak, respectively, it seemed as though a sweeping pandemic plan might need to be finalized and acted on. But neither disease turned out to warrant the “nuclear option” of social distancing, and so the working out of a detailed plan, encompassing an initial flattening of the curve and everything that would follow, would have to wait.
As the decade drew to a close, the United States was prepared for a pandemic in some respects and unprepared in others. In October, 2019, a study conducted by the Johns Hopkins Center for Health Security ranked the U.S. first in the world in terms of pandemic readiness, in part because of its “robust” health-care system; even so, this was a relative measure, and the researchers took pains to point out that no country was truly prepared. (Despite its over-all ranking, the U.S. ranked nineteenth on measures such as public-health infrastructure and economic resilience.) The Trump Administration exacerbated the problem by disbanding the National Security Council’s pandemic team and defunding various public-health programs. But inattentiveness to the risks of a pandemic preceded Trump: when the millions of masks stored in the federal government’s Strategic National Stockpile were used up, during the 2009 flu pandemic, Congress failed to reappropriate the funds necessary to replenish them.
In retrospect, one of the biggest weaknesses in our pandemic planning was that many infectious-disease experts, including me, focussed on the threat posed by a novel strain of influenza. We feared a repeat of 1918—and yet, because we now have the technology to create and mass-produce a new flu vaccine in only a few months’ time, a flu pandemic isn’t necessarily the worst-case scenario. As we are currently discovering, designing and testing an entirely new vaccine against a never-before-seen infectious disease is a far more uncertain and daunting task. The fact that the novel coronavirus is RNA-based, like H.I.V., intensifies the difficulty. It’s possible that a vaccine will arrive this year—but many experts think that it could be two years or even longer before a safe and effective shot has been developed, tested, manufactured, and made widely available.
The challenge, therefore, isn’t just flattening the curve but keeping it flat—holding the line not for months but for years. In a study published in Science in April, researchers at the Harvard T. H. Chan School of Public Health estimated that, in the absence of a vaccine for the coronavirus, periods of social distancing would be necessary into the year 2022. (Their analysis was, in its own way, optimistic: it incorporated the possibilities of new treatments for COVID-19, increases in I.C.U. capacity, and the spread of durable immunity over time.) The researchers noted that, even after social distancing lets up, governments will need to continue tracking the virus and addressing occasional outbreaks. In that sense, there’s a good chance that the pandemic may not be over until 2024.
Some countries have adjusted their plans to match these timelines. The German government has established a standard that allows communities to reopen, close up again, and then re-reopen. If, in the course of a week, a community detects more than fifty new coronavirus cases per hundred thousand people, then social distancing measures are reinstated; the same thing happens if the virus’s “reproduction number”— which measures the average number of non-immune individuals whom someone with the coronavirus is likely to infect—exceeds one. This plan allows Germany to reopen in a measured, cautious, data-driven way, and to retreat when the virus threatens to reach an inflection point, beyond which it will begin spreading so fast that it becomes nearly impossible to contain. Most Germans accept that this system, and the restrictions it requires, will remain in place until there is a vaccine or another transformative treatment.
And yet, here in the United States, keeping our curve flat will require more than the establishment of a conservative target for new cases. The challenges facing us are vast and, in some respects, unique. Unlike New Zealand, Iceland, Taiwan, and the other island nations that have succeeded in controlling the virus, ours is a huge country with decentralized political and public-health systems. A state that succeeds in containing the virus can be reinfected by its less successful neighbors. Our politics are divisive, our President is obstructionist, and a wide swath of Americans doubt what scientists say and resist public-health mandates as a matter of principle. Even those Americans who take the virus seriously are not accustomed to thinking about disease as a social issue. During flu epidemics, Japanese citizens are quick to self-isolate, put on masks, keep their children out of school, and stay home from work. In the U.S., we’re used to going to work even when we’re sick and to sending our sniffling children off to school. Scattered, leaderless, and misinformed, we are not necessarily in a position to succeed.
To meet these geographic, political, and cultural challenges, the United States needs not just an adequate pandemic response but an extraordinary one. We need a plan directed by experts who are trained in controlling epidemics; those experts, in turn, require a centralized data-collection center managed by skilled epidemiologists at the C.D.C., capable of insuring accurate reporting from state and municipal health departments. Across the country, we need to start tracking and tracing new cases on a vast scale and analyzing information about which communities are most vulnerable, who is most likely to get sick and die, and the efficacy of medical treatments. In sum, we need a government that collects information, makes decisions based on it, and then collects more.
A target number for new cases is useless if we don’t know how many cases are out there. We need a federal government that throws its weight and its money behind comprehensive coronavirus testing. Faster and more accurate tests, such as the saliva-based kits being developed at Rutgers University, which can be used at home, must be standardized, manufactured, and widely distributed in our towns, communities, schools, and universities. If such tests can’t be widely distributed, then we need to fund and develop easy-to-access testing that can be conducted in drive-throughs, in drug stores, and via mobile vans. We need to train an army of workers to administer these tests. We’ll know that we have enough testing capacity when it’s easy for anyone experiencing cold-like symptoms, loss of smell, dry cough, shortness of breath, muscle pain, sore throat, vomiting, diarrhea, or fever to get a test immediately. Tests must also be abundantly available to people who have had contact with someone suffering from COVID-19, and to those who are at high risk—people who are older than sixty-five, have chronic medical conditions, or live in close quarters with others.
Across society, we need businesses, schools, universities, and other institutions to confront the challenges of keeping the curve flat in the long term. Businesses need to give up on the idea of a near-term return to normal and commit to letting people work from home or in staggered shifts until a vaccine or other treatment becomes available. Restaurants and bars should recognize the risks that hasty reopenings pose to both patrons and staff, and keep their indoor spaces closed to customers. Colleges need to accept that their students are as capable of transmitting the virus as other adults are; instead of promising, unrealistically, to trace and test students who drink and party in dorms and off campus, they should shift to distance learning until the crisis is over. Making these responsible decisions will be financially painful—and so the government should step in with aid packages to help.
On June 25th, the American Academy of Pediatrics recommended that elementary, middle, and high-school students return to classrooms this fall, citing the low incidence of COVID-19 among young children and the well-established negative consequences of having school interrupted. For millions of American parents and children, for many reasons, going back to school will be a relief. And yet the harsh truth is that we don’t know very much about the long-term effects of coronavirus infection in children, or about how widely kids who are infected can spread the virus to the older people around them. Schools that open need money to mask and test everyone. Schools that stay closed need money to adapt to distance learning. Many schools that invest in reopening will have to close when the virus surges. Federal support for these efforts, too, is vital.
Holding the line against the virus will require still other changes. Masks should be mandatory in shared social spaces. Air travel should be restricted and reconfigured. States should be testing and quarantining international and domestic travellers. Almost certainly, we will have to make adjustments we haven’t yet anticipated. In an ideal world, government, at every level, would be behind such changes. But the tragic reality is that, at least for now, government recalcitrance is part of the American coronavirus endurance test. This means that, to a great extent, it’s up to American citizens, as individuals, to hold the virus in check until scientific reinforcements arrive. Individually, we must opt to wear masks in public, to wash our hands frequently, to separate ourselves from our families if we become ill. Individually, we must commit to practicing the “three D’s” of respiratory-virus hygiene: keeping our distance, and limiting the diversity and the duration of interactions outside our households. We must choose to ignore the ill-informed politicians and business leaders who are telling us that it’s perfectly fine to congregate, that the virus isn’t a real threat, and that the crisis is over. We must refuse to give up on flattening the curve. It’s up to us to hold the line until our government catches up.
The alternative is the path that D. A. Henderson suggested: “Cull the herd.” I have no doubt that, when he said those words, he hadn’t thought them through. No one in that crowded ballroom imagined a stubborn, persistent pathogen like the novel coronavirus; we were thinking of influenza, which tends to burn out as temperatures rise. And none of us could really imagine the quantity of death and social division that such a policy would entail. It’s clear now that the coronavirus pandemic, if it’s poorly managed, could rival not just the 1918 flu pandemic but also the Black Death of the fourteenth century and the cholera pandemics of the nineteenth century in terms of death toll. We will see millions more cases worldwide and hundreds of thousands more deaths at a minimum; we could vastly exceed those numbers if containment fails before treatments are ready. And those deaths will be concentrated among the poor, the vulnerable, and the marginalized. The collective achievement of flattening the curve in the early months of the pandemic will be meaningless by comparison.
When I began my own work on flattening the curve, I experienced it as an abstract historical exercise—an intellectual puzzle to be solved. I didn’t fully imagine the reality we are currently experiencing, either. Now, in the hospital and at the bedside, I have seen how rapidly and viciously the coronavirus attacks and kills. In late February, my eighty-three-year-old mother, who suffered from a neurodegenerative illness and resided in an assisted-living facility, caught the virus, sickened, and died within a day. The crisis is real, and so is the responsibility we have to ourselves, our families, and our communities. Having flattened the curve once, we must keep it flat until the virus can be defeated.
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