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With countries from Italy to the U.S. having waited too long to combat the coronavirus, many experts in public health and epidemiology are pleading with government officials not to compound the mistake by lifting stay-at-home and other social distancing measures too soon — and, in fact, to impose strict ones in U.S. states and cities that haven’t.

But from the World Health Organization to New York Gov. Andrew Cuomo to epidemiology modelers across the globe, there is growing recognition that the time will and must come to tiptoe back toward normalcy.

That recognition is driving the next life-and-death questions in the coronavirus pandemic: What is the exit strategy? How will we know when it’s safe to implement it? If this first wave of outbreak eventually crests and dissipates, as it has in China, what’s the plan if the virus returns with a vengeance in a few months? Can that plan be less disruptive to livelihoods and ordinary existence than the panicked responses in many western countries over the last month, and more like the surgical strikes that seem to have succeeded in Singapore and South Korea?


The “when can we?” research, unfortunately, is playing out against a highly politicized background. President Trump on Tuesday vowed to return the country to “normal” by Easter, April 12. But while the epidemic in the U.S. is still far from under control, much less peaking, apolitical experts are nevertheless cautiously starting to figure out how smarter, targeted approaches could serve as an off-ramp for the current control measures and how to do better next time, especially if Covid-19 cases rebound after the current outbreak fades.

“You can’t stop the economy forever,” Cuomo whose state has more Covid-19 cases and stricter restrictions than any other said in a news conference on Monday. “So we have to start to think about, does everyone stay out of work? Should young people go back to work sooner? Can we test for those who had the virus, resolved, and are now immune and can they start to go back to work?”


He and others who cringe at the very thought of relaxing social distancing, including many infectious disease experts, are asking how to do it right, or at least better. There is reason to hope that will be possible. An emerging consensus points to aggressive tracing of contacts of sick people, much broader testing, targeted quarantines, and new online tracking technology as strategies that would facilitate the easing of social distancing measures.

Scientists including infectious disease epidemiologist Marc Lipsitch of the Harvard T.H. Chan School of Public Health, one of the most forceful voices against easing up prematurely on containment and mitigation, conclude in a new paper that in a best-case scenario, “summertime social distancing can be less frequent.” After that, they explain in an analysis published as a preprint on Tuesday, their mathematical model of how people interact and how infections spread suggests that, if the epidemic returns, “aggressive contact tracing and quarantine – impractical now in many places but more practical once case numbers have been reduced and testing scaled up – could alleviate the need for stringent social distancing to maintain control of the epidemic.”

Authoritative support for the possibility of an exit strategy and more targeted countermeasures against a second wave came on Wednesday. Researchers at Imperial College London, whose earlier model projected apocalyptic levels of Covid-19 deaths across the U.S. and United Kingdom absent near-China-level lockdowns and other forms of social distancing, concluded that in once-frozen cities such as Wuhan, “intermediate levels of local activity can be maintained while avoiding a large outbreak.”

The new data, they wrote, “suggest that after very intense social distancing which resulted in containment, China has successfully exited their stringent social distancing policy.” There are indeed “exiting strategies,” Neil Ferguson and his colleagues conclude, and they “can inform decision making processes for countries once containment is achieved.”

The optimism depends on first controlling the current outbreak, however. In many places, that isn’t even in sight, as many hospitals careen toward collapse and U.S. cases and deaths soar. In a TED video chat on Tuesday, Bill Gates warned that re-opening commerce too soon would be tantamount to “ignor[ing] that pile of bodies over in the corner.”

The point of lockdown measures, WHO Director-General Tedros Adhanom Ghebreyesus said during a briefing Wednesday, “is to enable the more precise and targeted measures that are needed to stop transmission and save lives.”

If today’s stringent measures remain, and people adhere to them better than they have, the curve will not only “flatten” but peter out. In that case, key decisions going forward will focus on how to keep Covid-19 cases to a manageable level during a second outbreak.

Singapore subway
Commuters wear face masks on the subway in Singapore on March 18. CATHERINE LAI/AFP via Getty Images

The approach getting the most support is one that experts have long doubted could work with a respiratory virus: aggressive case finding, contact tracing, community surveillance, isolation of cases, and quarantining of contacts. Both Singapore and South Korea used that, allowing them to make tactical decisions about schools (mostly open in both countries) and public movement, sparing them from shutting down to the extent that the U.S. and many countries in Europe have.

That suggests an exit strategy for the U.S. “If the case numbers are really low enough, you can do a more Singapore-like or Iceland-like strategy of following individual cases rather than just social distancing,” Lipsitch told reporters on Tuesday. (It’s not clear what “low enough” means, though it would be based in part on hospital capacity.) If public health agencies conduct intense testing, including of people without symptoms, and identify and test their contacts, he said, “you may be able to get away potentially with less social distancing the second time around, because you’re also controlling the individual cases.”

The value of doing so would be enormous, since it could replace the draconian steps that are the only option when chains of viral spread can’t be tracked but that have been financially ruinous, especially to low-wage workers. Although “the feasibility of [widespread testing and contact tracing in the U.S.] remains to be seen and requires a lot of coordination that doesn’t yet exist,” Lipsitch cautioned, there are at least two reasons to think it could be brought into existence: technology and weather.

Earlier this month Health and Human Services Secretary Alex Azar called contact tracing “the basic blocking and tackling” to contain an epidemic. Infectious disease experts have never thought contact tracing could work for respiratory diseases (it isn’t done for flu): It takes so long and these infections move so fast. But in 2020, there’s an app for that.

One called Private Kit: Safe Paths, developed by scientists at the Massachusetts Institute of Technology, would upload data to a privacy-protected site on cases and where they had been. Users who had been in close contact with that person would get a notification and could then isolate themselves for two weeks, slowing viral spread from people without symptoms. In contrast, simply interviewing a single case and identifying that person’s contacts takes an average of 12 hours, said MIT’s Francesco Benedetti. Worse, people can’t remember exactly where they were, let alone what strangers they brushed against or breathed on, two weeks ago.

But the near-instantaneous contact tracing made possible by technology “is one of the most important steps we can take, the infectious disease specialists we worked with tell us,” Benedetti said. “This addresses the need for speed.” The technology should be ready for nationwide use “soon,” he said.

It mimics what Singapore was able to accomplish: banning mass gatherings, yes, but not closing schools, and — crucially — interviewing patients and using security camera footage to identify those they encountered and order them into home quarantine. That severed numerous transmission chains.

In Israel, researchers are testing a similar tool to identify and predict virus hot zones. A smartphone-based questionnaire asks people their age, gender, and location as well as whether they have such Covid-19 symptoms as cough, fatigue, shortness of breath, and diarrhea. Some 320,000 Israelis have filled it out, revealing a significant increase in reported symptoms in places where known patients passed through, said Eran Segal of the Weizmann Institute of Science — an indication that the survey can augment laborious contact tracing by health workers. Israel’s case count reached 2,170 cases on Wednesday.

The tool lets a country (or state or city) “identify, ahead of time, regions of outbreak of the virus,” Segal said. “This will allow health officials to deploy testing in a smarter way, identify those individuals who are infected, and isolate them. It can also allow tightening the lockdown in specific locations but more importantly, relieving the lockdown in other regions where no outbreak is expected.”

That suggests not only an exit strategy but also a next-time strategy, he said. “When we eventually release the population from lockdown, such a tool can be critical in management of the spread of the virus, as it may ahead of time inform us of regions where the outbreak is re-emerging.”

It will take weeks, and maybe months, to refine and deploy tools like these. But we may have that breathing room.

How summertime temperatures will affect the virus remains unknown. But there are reasons for optimism.

Although the research is far from definitive, several studies in China find that higher temperatures do decrease Covid-19 incidence. One, a modeling study posted to the preprint site medRxiv on Tuesday, “confirmed that transmission rate decreased with the increase of temperature, leading to further decrease of infection rate and outbreak scale,” scientists at China Medical University wrote. One reason may be that this coronavirus, like that which caused the SARS epidemic in the early 2000s, can’t survive on surfaces as long in warmer weather.

The new coronavirus emerged during flu season, making people wonder — will cases start going down as spring rolls around, just like the flu? Hyacinth Empinado and Alex Hogan/STAT

“Other coronaviruses are seasonal,” said Jeff Shaman of the Mailman School of Public Health at Columbia University. “So we might catch a break here.”

The decision by the U.S. and other countries to close businesses, cancel events, issue stay-at-home orders, and ban large (and now small) gatherings was partly driven by the early mathematical model created by the Imperial College team. That drove policies that prioritize widespread and strict countermeasures rather than more targeted ones.

Now that more experts have dug into the model, they are questioning whether officials drew the right conclusions and, especially, whether economy-crippling policies can be avoided once the first phase of the outbreak passes.

For instance, the Imperial College model does not allow for the possibility of detecting asymptomatic individuals through mass testing or contact tracing, as South Korean did instead of issuing stay-at-home orders. With such mass testing, infected people can be identified even before symptoms appear and can isolate themselves for two weeks.

The critics’ intent is not to slam the highly respected Imperial College team, but to suggest that different assumptions can illuminate the exit strategy and the “next time” strategy.

“The model does not account for important individual-level behavior changes that many people adopt to protect themselves in epidemics,” said epidemiologist and modeler Gerardo Chowell of Georgia State University, including “increased hand washing, staying home if sick, reducing social activities, and wearing a face mask.” He agrees that simple face masks do not keep the virus out very well, but they help keep it in, especially when infected people cough or sneeze or even speak. Widespread use of face masks, as in Japan and other countries in east Asia, would be less disruptive than lockdowns.

Another exit strategy, he and others argue, is targeted intervention. “Factors such as population density, urbanization, environmental factors including temperature and humidity, and connectivity to the rest of the world have been shown to drive transmission rates,” Chowell said. “The intensity of the social distancing interventions have to be implemented in light of the local infectious dynamics,” as does the timing of any easing of restrictions.

The question of timing is, of course, key. “The conservative approach is to wait till there are no new cases in an incubation period,” said Yaneer Bar-Yam of the New England Complex Systems Institute, who uses the science of complex interactions to create mathematical models of epidemics. But once the peak of an outbreak has passed in any region, and if travel restrictions prevent imported cases, “we have every reason to believe [contact tracing and isolation of cases and contacts] can work.”

He, too, sees hope for a more targeted approach soon. “Travel restrictions prevent spreading the disease from areas that have it to those that don’t,” Bar-Yam said, “and enables relaxing restrictions earlier in areas where it has been eradicated. Testing enables rapid isolation of individuals so we don’t have to isolate as many people in order to stop the outbreak.”

More and more modelers are discussing “precision quarantine,” as Momiao Xiong of the University of Texas Health Science Center and colleagues in Shanghai call it, to “slow down and keep people from transmitting the disease.” That could help with both an exit strategy and a next-wave strategy.

“Even in a semi-locked-down state, you can prioritize [for testing and contact tracing] people in grocery stores, banks, delivery, and others who come into contact with a lot of people and are therefore most at risk of being super-spreaders,” said Columbia’s Shaman. They should be tested repeatedly.

At the beginning of the outbreak it was unclear if super-spreading occurred, as it did with SARS in 2003, but researchers in China have found that it does: One Covid-19 patient infected 52 others, they reported on Monday.

“The main thing we want to do [during any summertime respite from the outbreak] is get ourselves ready to do extensive testing,” Shaman said. “If it’s sensitive and specific enough, it would allow us to track and isolate people who are infected and their close contacts.”

If people do not carry the virus, there is no reason they couldn’t gather in large groups, he said. To make that as safe as possible, potential super-spreaders — those who come into close contact with hundreds of people — should be tested and tested again, both now and going forward.

Testing shouldn’t wait until cases start mushrooming again, as China’s experience shows. Without the lockdowns and other measures in Hubei province, scientists there estimate, the number of Covid-19 cases would have been 67-fold higher. Early case detection and isolation prevented more infections than travel restrictions, they conclude, but speed is key: If countermeasures had kicked in three weeks earlier, China would have had 95% fewer cases.

An analysis of how China, Hong Kong, South Korea, and Singapore controlled the coronavirus outbreak also concluded that the strategy with the greatest impact was rapid testing, contact tracing, and quarantining cases and those they might have infected, for two weeks. That was more effective than travel bans, lockdowns, and school closings, Andrew Tatem of England’s University of Southampton and his colleagues found.

If policymakers needed any more reasons to prepare for extensive testing and the targeted countermeasures that would allow, it’s this: Covid-19 could well return next fall with a vengeance because of today’s social distancing measures.

There will be “a high proportion of susceptible individuals in the population,” Harvard’s Lipsitch and his colleagues explained in their analysis. That could lead “to an intense epidemic … in the late autumn and winter.”

Even  then, the world will likely not see the end of this coronavirus. Instead, they conclude, it will “circulate seasonally with winter peaks in subsequent years.”

Andrew Joseph contributed reporting.

  • Another exit strategy would be to anticipate and prepare for the next wave of illness (before access to global vaccination) via the reallocation of resources and creation/implementation of nurse training with volunteers identified in the general population. One of your previous article’s commentators (Elizabeth Tea) reported on the experience of her grandmother, a nurse during the Spanish Flu, who recalled losing zero patient as she nursed them back to health in their home. It’s important to remember that the action/function of this type of medical professional is precisely ‘to nurse.’

    CNN’s recent story trying to explain Germany/South Korea’s better outcomes may reside in the ratio of nurses to population. And I quote: “Among the nine countries with the highest number of Covid-19 cases, the country that has the highest nurse rate also has the lowest death rate from the disease. Germany has 13.2 nurses per 1,000 (echoing a trend for high nurse numbers throughout Northern Europe) far above the other heavily Covid-19 affected countries.” France, for example, has had extended periods of strikes during the past year demanding more resources and recognition. They are now paying with their lives for the nonchalance of government and media alike. But maybe now they will have been heard loud and clear. Let’s hope the U.S. gov’t and the U.S. media also develop the art of active listening and the virtue of decisive action.

  • In both this article and the one printed today by Helen Branswell, Japan is given short shrift, which is disturbing since it seems to reflect an a priori bias for “aggressive” actions that are not fully supported by the facts. Japan is a much bigger country than Signapore, South Korea, and Taiwan and was one of the first countries to be affected by COVID-19, and yet it has managed to contain the virus without imposing a lockdown, or for that matter, undertaking a broad-scale testing program. As Gerardo Chowell suggests here, the nearly universal use of face masks, combined with common sense hygiene practices, seems to have averted disaster in that country. Yet in several recent surveys of national approaches to COVID-19, Japan’s experience is often totally ignored. Those articles that do address Japan’s mystifying success treat it as a case of sheer luck and often predict a comeuppance in the not too distant future. Such articles, however, never really explain why a disease as contagious as COVID-19 would wait to exploit the less restrictive environment in Japan when it continues to ravage countries, like Italy, with far more severe containment regimens. It’s almost as if journalists resent Japan for anchoring a compelling alternative to aggressive government actions, which “everyone knows” is the appropriate course of action. But wouldn’t it make more sense to explore whether Japan’s story may have something to teach us about how to mitigate the spread of COVID-19 without shutting down the global economy. The widespread use of face masks is often shot down by health officials in America, but if the virus is as highly transmissible as new data suggests, then it’s quite likely that a vast majority of citizens in hot spots are already infected or even in a post-recovery phase. Some researchers are already making this claim. If that’s the case, testing would have little value for containing the virus, but face masks would provide a means for controlling spread.

    The case of Germany may provide another reason for reconsidering draconian actions. Before the existence of COVID-19 became an international story, Germany was struggling with one of the worst outbreaks of flu in recent history. Looking at the unusually low number of deaths that country attributes to COVID-19, it seems at least possible that at least some of the rise in flu-related illnesses and deaths are actually attributable to the initial spread of coronavirus. If so, it’s currently low fatality rate may suggest that Germany is already past the peak of infection and that its current aggressive measures may be a case of shutting the barn door after the horse has bolted.

    • One benefit provided by simple face masks, even homemade ones, is that it keeps a individual from touching their face very much – in particular their nose and mouth. Ideally a person would wash/disinfect their hands immediately after removing their mask. As mentioned, a mask also reduces the ability of an asymptomatic person from spreading the virus. To me, these two benefits of a populace wearing masks when out and about are substantial.

  • Another exit strategy would be the reallocation of resources and nurse training in the general population. One of your previous article’s commentators (Elizabeth Tea) reported on the experience of her grandmother, a nurse during the Spanish Flu, who didn’t lose one single patient as she nursed them back to health in their home. It’s important to remember that the act of such medical professionals is precisely ‘to nurse.’ CNN’s recent story of Germany/South Korea’s better outcomes was the ratio of nurses to population. “…higher numbers of nurses may reflect one of two beneficial factors..: first, that nurses, the backbone of hospital (and especially ICU) care, are essential to patient management and, ultimately, survival.”

  • Doy Quimico 73/77 UNAM. Literalmente mejor vivir en una burbuja de Jabón. Esta comprobado q el jabón mata el COVID-19 entonces habra que fumigar las ciudades con particulas de jabon inocuas para la población pero letales para el virus

  • Yea, seems like it is exactly what they wanted. Before you know it, we all get chipped and no more physical currency. If people can’t see what is going on here, then I guess we are all to blame. Don’t be stupid, governments around the world are using this to take away rights, line their own pockets, but tell us it is for our own safety.

    • Seems you are not aware of government activity such as free financial support to individuals and businesses, next to zero interest rate, and money-printing in overdrive. Please don’t be paranoid, and do get / stay well-informed.

  • You can’t use a map unless you know where you are and know if you are going in the right direction. Before we do RANDOM testing of 100 individuals with antibody testing (to determine who has had Corona and are immune) and 100 swabs to determine number of active cases in the population, and repeat this every day, we have no idea where we are and where we are going. If we decrease social distancing and the random test still shows more immune people and less active cases, we can continue, if not, it is back to lockdown ASAP. But we have to know. DO THE RANDOM TEST. Aren’t there any scientists out there?

    • Test for antibodies are just being developed and not yet deployed except in small quantities. Of course there are scientists out there, they just don’t have the tools to do a RANDOM TEST.

  • Travel restrictions were critical in the initial phases of the pandemic (this is not “racist” just standard old fashioned public health policy), and in addition to China, Singapore, Taiwan, Hong Kong, Japan(?) and Australia and New Zealand, Israel also has called for even more stringent 14 day home quarantines on people entering the country. While these countries have done great jobs relative to the West (and Iran) increasingly their citizens are returning with infections. While obvious enough, asymptomatic and mild cases can slip through screening and continual, vigilant tracking is required to minimize new clusters from “community spread” cases. While travel restrictions have been critical, packed populations (as in much of SE Asia) using public transport will likely eventually allow breakthrough. PCR testing for the virus has been emphasized, but eventually antibody serological testing will be needed to see who have been infected but recovered; that should fill in lots of gaps in tracing, and may also identify children as major spreaders of the virus.

  • I am glad to see discussions with alternative views. Tracing seems to be the most sustainable way to deal with the new normal. Closing down the economy seems short-sighted since the USA greatest weapon is our economic engine. The less effected areas could bolster the economy while N.Y. and CA fights the frontline. Full on shut down not supported by data(or at least some) makes us more vulnerable. New custom wash your hands, wipe as you go so gas pump,pin pads,atm…

  • The wild card left out is that Americans are both accustomed to having total freedom and are in many cases foolish (using a kinder word there than I would like). They literally lined up chest to back waiting in lines to get into stores to buy supplies. They traveled to places they should not have and in some cases didn’t have a care in the world because they were young and seemingly to them immune, while not thinking about their own senior family members.

    I agree that a targeted approach tailored to each individual area can work, but it has to be done quickly enough and strictly enough to work. Likewise, opening up individual areas can also work but…travel may have to be discouraged or stopped unless absolutely necessary. As an example, the only cases in my area were brought in by people who traveled and then went to work and exposed other people, some of whom became infected. Self discipline in not in many American’s vocabulary…..

    • Given that a significant number of positives remain asymptomatic (Vo, Italy, Korea etc.) and that the virus has been in the US since 2019, “containment” and even flattening the curve is delusional. Quarantine the vulnerable population, open the economy back up, let it run its course to achieve herd immunity, treat the severe cases with Chloro and Zn (or other Zn iontophores), and get through this. Belgium and the UK started in the right direction but folded under political pressure.

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