Lessons on flattening the curve: Evidence in favor of widespread testing and social distancing during the COVID-19 pandemic

By Ryan Hylton

“We’ve got a choice to make. Do we want to follow the trajectory of a South Korea, where they had aggressive mitigation measures and everyone really leaned into this issue, or do we want to follow the trajectory of Italy where we’re seeing a rapid increase in cases and more deaths?”1

The U.S. Surgeon General, when addressing the press on March 16th, looked to examples from other nations when discussing the “critical inflection point” the U.S. finds itself in. As the coronavirus outbreak spreads rapidly across America, public health officials and politicians are tasked with determining the proper course of action. Outbreaks in other countries have been ongoing for a number of months and there is much to learn from the outcomes of those cases. Two heavily antithetical examples are Italy and South Korea. Both countries saw the virus spread rapidly in late February, and yet their current situations are very different2 (see Figures 1 and 2). South Korea has seen a swift decline in the number of new cases each day, while some parts of Italy embody a nightmarish scene where hospitals are overcrowded and there is limited access to ventilators and other supplies needed to treat all COVID-19 patients3. The U.S. coronavirus outbreak is still in its early days, and there ought to be great effort put towards avoiding what has happened in Italy. The question is: What steps can we take to make the U.S. outbreak look more like South Korea’s and less like Italy’s?

With all of the uncertainty surrounding COVID-19, it is clear that the disease is most lethal to the elderly4,5. That being said, the present dichotomy between the two aforementioned nations may be attributed in part to demographics. Italy, for instance, has the 2nd oldest population in the world, with 28.6% of its population 60 years of age or older5. In South Korea, that number is only 18.5% (ranked 53rd)5. More importantly, South Korean COVID-19 cases have primarily been among patients in their 20s (~30% of cases)5. Fortunately, in the U.S., only ~16% of the population is 65 or older3.

Another major factor, and one that is more actionable, is the governmental and public health response. On March 9th, Italy entered in a mandatory lockdown with schools and most businesses in the country being closed for the foreseeable future6. However, it now appears that these actions came too late. There is a growing consensus that Italy’s first COVID-19 cases actually hit in early January7. The virus seems to have infected mostly young people first, and because they often carry the disease with mild or no symptoms, they were able to infect a large set of the population before the government was aware of the problem and able to react justly7. The U.S. is currently approaching a lockdown of sorts, with many schools, restaurants, bars, theaters, and other “non-essential” businesses closing for the next few weeks. These decisions by lawmakers have not been met with open arms in many parts of the country as there is great concern about the short and long-term economic and social effects of these actions.

This level of enforced “social distancing” is not without precedent. The most lethal pandemic in modern history, the Spanish Flu, killed 675,000 people in the United States in 19188. A 2007 paper studied the role of non-pharmaceutical interventions (NPIs) (including moves like school closures, theater closures, and isolation policies) in the reduction of viral spread during that pandemic9. They showed a ~50% decrease in peak death rates and less steep epidemic curves in cities where multiple NPIs were implemented early in the outbreak. This is most readily apparent in the graph below which shows the death rates in two cities, Philadelphia and St. Louis, during the pandemic (see Figure 3). St. Louis began instituting NPIs very soon after the first reported flu case (2 days), whereas Philadelphia’s response was comparatively delayed (16 days), and this resulted in St. Louis death rate being much less than Philadelphia’s.

Interestingly, South Korea did not implement a full lockdown during their COVID-19 outbreak. Instead, their focus was on increased testing. As of March 8th, South Korea had issued 3,692 tests per million people, one of the largest rates in the world5. Italy, by contrast, has tested 826 per million and has the largest number of cases and deaths of any country other than China5. Widespread testing enables the discovery of early infections so that people can be quarantined prior to unknowingly spreading the disease to relatives, coworkers, and the general public. Alongside testing, health officials have implemented public awareness campaigns, including mobile phone alerts that inform citizens when someone in their district has tested positive, how the person became infected, where they are being treated, and the last places they visited before being tested2,10. A lack of testing is another issue the U.S. is facing, as many people are being turned away from clinics because a test isn’t available in their region5.

Fortunately, the U.S. is heavily enforcing social distancing early on in its outbreak. If the nation’s healthcare system is to keep up with the demand from this novel coronavirus, it appears it will also be vitally important that widespread testing is implemented in addition to the school and business closures we have already seen. In the meantime, we can all do our part by washing our hands, and maybe spending less time at work and more time watching Netflix.


  1. https://www.cbsnews.com/news/coronavirus-us-cases-south-korea-italy-surgeon-general-jerome-adams/
  2. https://www.nytimes.com/interactive/2020/world/coronavirus-maps-italy-iran-korea.html
  3. https://www.wired.com/story/why-the-coronavirus-hit-italy-so-hard/
  4. https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf
  5. https://www.cnn.com/2020/03/16/opinions/south-korea-italy-coronavirus-survivability-sepkowitz/index.html
  6. https://www.vox.com/future-perfect/2020/3/20/21179040/coronavirus-us-italy-not-overreactinghttps://www.wired.co.uk/article/coronavirus-italy
  7. https://www.cdc.gov/flu/pandemic-resources/1918-pandemic-h1n1.html
  8. Hatchett RJ, Mecher CE, Lipsitch M. Public Health Interventions and Epidemic Intensity during the 1918 Influenza Pandemic. Proceedings of the National Academy of Sciences of the United States of America. 2007;104:7582-7587.
  9. https://www.sciencemag.org/news/2020/03/coronavirus-cases-have-dropped-sharply-south-korea-whats-secret-its-success

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