As the harms of social distancing become more and more apparent, Americans may start to wonder: Are we overreacting to the coronavirus pandemic?

A few people (although not most of the public) seem to think so. Some federal officials, from President Donald Trump to Rep. Andy Biggs (R-AZ), have asked if “the cure is proving worse than the disease itself.” Protesters in several states, including Michigan, Ohio, and Kentucky, have called for lockdowns to end, arguing that the damage to the economy is too much to bear.

This is a question public health experts and officials expected from the start. As Kent State University epidemiologist Tara Smith told me, “It’s the paradox of public health: When you do it right, nothing happens.”

The problem with proper prevention, the linchpin of many public health strategies, is that there’s no clear indication when it works. There’s no public celebration when a coronavirus case or death doesn’t happen.

And in the meantime, the economic damage of closing down America is readily apparent. Some economists warn that the unemployment rate could surpass 30 percent. About 22 million have filed unemployment claims since social distancing measures took effect in March. The lines for food aid are stretching for blocks across the country. It’s now much more difficult — if not impossible — to visit family and friends and partake in many favorite hobbies and activities.

In other words, the benefits of social distancing aren’t very visible, while the pain from it is. That creates a situation in which it can be easy to take for granted that social distancing is, according to experts and models, likely preventing hundreds of thousands of deaths in the United States.

But it’s important to remind ourselves what we’re doing here. The US wants to avoid getting to the point where it’s obvious we did something wrong and need to correct course. We want to prevent what happened in Italy, Spain, or New York from happening across the country. That means reacting not just to what’s visible to us in the present, but what’s potentially in the future. Doing that will always at some level seem like an overreaction, even if it’s the right call.

“Anytime you are dealing with an outbreak, if it appears like you overreacted, then you probably did the right thing,” Krutika Kuppalli, a fellow in the Johns Hopkins Center for Health Security Emerging Leaders in Biosecurity program, told me.

That’s particularly true for coronavirus. There’s still a lot we need to learn about the virus, but we do know it seems to spread at least in part through people who aren’t showing any symptoms. That means it can be spreading in communities without anyone — not even the people who are infected — knowing it. That requires taking action before the virus is clearly visible, at least without mass testing, in a community.

There’s also evidence from past outbreaks, particularly the 1918 flu pandemic, that reacting quickly and aggressively — even before a disease clearly poses a threat — is crucial both to saving lives and, in the long term, potentially keeping the economy intact.

Yes, it demands a shared sacrifice at this time. But it’s worth it. The alternative — that we let up to millions of people, including our friends, family, and peers, die — is so bad we need to do everything we can to prevent it.

The coronavirus requires what might seem like an overreaction

It’s true that we still don’t know enough about the SARS-CoV-2, the novel coronavirus. That can seem like a reason to not do much: Maybe the virus isn’t as contagious or as deadly as we think it is. Maybe it’ll die down in the summer with warmer weather. Maybe only specific segments of the general population are really vulnerable.

That’s all possible. But remember: Even if all of this and more turns out to be true in the future, the reality is we simply don’t know that now and didn’t know it before. We have to act with the best information we have. And that information suggests the coronavirus is really bad — whether it’s a huge outbreak in Wuhan, China, that forced the country to lock down, the outbreak in Italy that overwhelmed its health care system, or the outbreak in New York that has turned the US into the world’s leader in reported cases and deaths (with more than 694,000 and 31,000, respectively, as of April 18 — and both figures are likely underestimates).

We also know that the coronavirus can spread from people who don’t have symptoms yet or will never develop significant symptoms. That could mean the disease is less deadly than we think; if there are a lot more asymptomatic carriers than we realize, it could mean a way smaller fraction of the people who are infected are dying.

But it also means that the virus can spread before it’s clearly visible in a community. That’s been particularly exacerbated by America’s poor testing capacity — a result of both poor pandemic preparedness generally and President Trump’s slow reaction to the outbreak — leaving the country unable to quickly test people to see if there’s asymptomatic spread. (As a result, we actually underreacted to Covid-19, and have continued doing so by failing to scale up testing.)

“Your chance of the first case being the one that comes to your attention is very, very, very, very small,” George Rutherford, an epidemiologist at the University of California San Francisco, told me. “By the time you have the first death, you have to figure that there’s been three full weeks of transmission, and there are at least several hundred cases in the population.”

So once a city, state, or country is reporting a few Covid-19 cases and especially deaths, it’s typically safe to assume there is a much bigger outbreak going on — just one that’s not fully visible, at least yet, to the public. Given that coronavirus cases and deaths can double every few days, it’s important for the public and officials to act quickly and preemptively to stop exponential growth.

It’s in this context that it’s so important that countries act, though it can feel like an overreaction. If you wait until there are already a bunch of cases or deaths in your community, it could be too late to prevent an outbreak that even extreme social distancing might be unable to get under control for weeks.

Consider the stories of California and New York. California actually reported some of the first coronavirus cases and deaths in the country — including the first case of community transmission — but now New York has 14 times the Covid-19 deaths as California. There are important differences between the states, such as New York City’s much higher population density and greater public transportation use. It’s also possible New York just got unlucky: “There’s the possibility that there were just more introductions of the virus in the East Coast, in the New York area,” Jeffrey Martin, an epidemiologist at the University of California San Francisco, told me.

But one likely contributor is that California, particularly the San Francisco Bay Area, reacted quicker to the outbreak. The Bay Area issued America’s first shelter-in-place order on March 16, and California issued a statewide stay-at-home order three days later — while New York didn’t until March 22. Even before the government mandates, some parts of California seemed to adopt social distancing early: Restaurant data from OpenTable suggests that seated dining on March 1 was down 2 percent in New York City, but it was down 18 percent in San Francisco. (Though it was only down by 3 percent in Los Angeles, so not every place in California acted the same.)

The extra days and weeks may not seem like that much time. But when coronavirus cases and deaths can double every few days, that short time span can be important. “With this virus, days, and even hours, matter,” Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, told me.

It could have been easy at the time to make the case that California and particularly the Bay Area were overreacting, given that the entire state had fewer than 25 deaths when it locked down. But it ultimately seems like it was the right decision.

Previous research is clear: Outbreaks require strong, early action

While there’s a lot about the coronavirus and the nature of this outbreak that we still don’t know, research from the 1918 flu pandemic, which was linked to as many as 100 million deaths globally and about 675,000 deaths in the US, provides some useful evidence for strong, early action.

A 2007 study in PNAS found the places that took quicker action on social distancing — closing schools and banning big public gatherings — saw better outcomes:

[C]ities in which multiple interventions were implemented at an early phase of the epidemic had peak death rates ≈50% lower than those that did not and had less-steep epidemic curves. Cities in which multiple interventions were implemented at an early phase of the epidemic also showed a trend toward lower cumulative excess mortality, but the difference was smaller (≈20%) and less statistically significant than that for peak death rates.

One example cited in the study is the difference between Philadelphia, which was slow to act, and St. Louis, which was faster. As this chart shows, St. Louis did a much better job of flattening the curve and averting excess deaths:

Another 2007 study, published in JAMA, validated the findings — showing places that acted earlier and more aggressively saved lives. But this study also demonstrated the importance of sustaining social distancing measures: When cities, including St. Louis, pulled back their measures too quickly, they saw a spike in deaths.

Here’s how that looks in chart form, with the line chart representing excess flu deaths and the black and gray bars below showing when social distancing measures were in place. The highest peak comes after social distancing measures were lifted, with the death rate falling only after they were reinstated.

This did not just happen in St. Louis. Analyzing data from 43 cities, the JAMA study found this pattern repeatedly across the country. Howard Markel, an author of the study and the director of the University of Michigan’s Center for the History of Medicine, described the results as a bunch of “double-humped epi curves” — officials instituted social distancing measures, saw flu cases fall, then pulled back the measures and saw flu cases rise again.

Notably, the second rise in deaths only appeared when cities removed social distancing measures, the JAMA study found: “Among the 43 cities, we found no example of a city that had a second peak of influenza while the first set of nonpharmaceutical interventions were still in effect.”

While invoking social distancing is often presented as a choice between saving lives and sustaining the economy, there’s also some preliminary evidence that the early, aggressive actions help the economy in the long term as well. Dylan Matthews covered a recent study along these lines for Vox:

Economists Sergio Correia, Stephan Luck, and Emil Verner released a working paper (not yet peer-reviewed) last week that makes this argument extremely persuasively. The three analyzed the 1918-1919 flu pandemic in the United States, as the closest (though still not identical) analogue to the current crisis. They compare cities in 1918-’19 that adopted quarantining and social isolation policies earlier to ones that adopted them later. Their conclusion? “We find that cities that intervened earlier and more aggressively do not perform worse and, if anything, grow faster after the pandemic is over.”

The basic problem is that a lot of people getting sick and dying is also pretty bad for the economy — potentially worse than temporarily shutting the economy down.

The risk for us now, by believing we might be overreacting to the coronavirus pandemic, is thinking we can ease up on measures, doing it, and subsequently seeing a spike in Covid-19 cases and deaths. In fact, that already appears to be happening in some parts of the world; Asian countries that initially contained the outbreak, such as South Korea and Singapore, are now reporting signs of a second wave of cases after easing some of their restrictions.

None of this completely eliminates the possibility that we are overreacting. Maybe a year or two from now we’ll realize that we didn’t have to close down certain parts of the country. Or maybe certain segments of the population could have remained at their jobs. Or maybe the warmer temperatures could slow the virus’s spread more than we think (though heat hasn’t been enough in Singapore, where it’s currently 80-plus degrees Fahrenheit). We just don’t know.

But as public health experts have told me, it’d be much better to end up second-guessing ourselves about whether we overreacted than whether we underreacted and maybe caused the deaths of millions. Because that’s the risk right now, based on the best evidence we have.

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