Without Mass Testing, the Coronavirus Pandemic Will Keep Spreading

Countries such as South Korea that test thousands of people per day have slowed the outbreak. Other nations must adopt Seoul’s model before it’s too late.

Medical workers wearing protective gear take samples from a driver with suspected symptoms of coronavirus at a test facility in Goyang, north of Seoul, on Feb. 29.
Medical workers wearing protective gear take samples from a driver with suspected symptoms of coronavirus at a test facility in Goyang, north of Seoul, on Feb. 29. JUNG YEON-JE/AFP via Getty Images

When a patient arrived at a Chinese hospital with acute respiratory distress in mid-December 2019, there was uncertainty about what was causing these symptoms. Known pathogens were quickly ruled out: It was not SARS, MERS, or influenza—and, quickly, a novel coronavirus was detected. When doctors tried to raise the alarm, police threatened them, and health officials initially said they had no clear evidence of human-to-human transmission.

When China finally informed the World Health Organization of the outbreak through its China office on Dec. 31, 2019, it was clear the government was privately worried that it was not going to be easy to contain or manage.

By Jan. 23, China had 571 cases and a death toll of 17. Infectious disease specialists who create predictive models of epidemics immediately sounded the alarm about the new coronavirus disease—known as COVID-19—noting that China could experience 100,000 new infections per day with hundreds of millions of people becoming infected. By the following day, the central government of China had imposed a lockdown in Wuhan and other cities in Hubei province affecting 56 million people.

But even before these measures were implemented, the virus had already started spreading to Hong Kong and other countries such as Singapore, South Korea, and beyond. South Korea reported more than 2,000 total confirmed cases on Feb. 28. Then, in early March, something unexpected occurred: The exponential increase of cases in these countries stared to flatten. China has managed to keep its confirmed cases under 90,000, with daily new cases coming down. Italy, which recorded its first cases of COVID-19 on Jan. 30, has now lost more of its citizens (more than 6,000 as of March 23) to the disease than China has.

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The severe Chinese response bought other countries time, but not all leaders took advantage of it. Before the outbreak reached their shores, heads of state across the world each decided to plan—or not plan—for this outbreak in their own way. Some, such as U.S. President Donald Trump, downplayed the dangers on national television, while others, such as South Korean President Moon Jae-in, acted early and decisively.

Indeed, South Korea stands out as an exemplar. After one of the world’s largest initial outbreaks outside China, it has managed to bring daily new cases into relative decline without imposing draconian nationwide lockdown measures. Comparing Italy to South Korea shows how dramatic the differences can be. On March 1, Italy had only 1,701 cases and 41 deaths, while South Korea had 3,736 cases and 21 deaths. Three weeks later, on March 22, Italy’s caseload had exploded to 59,138, with 5,476 deaths, while South Korea’s total caseload had merely doubled to 8,897, with 104 deaths.

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The key to South Korea’s success has been speed and an early push toward mass testing, rigorous contact tracing, and mandatory quarantine for anyone near a carrier of the virus. The country, with a population of 51 million, tests more than 20,000 people a day at more than 600 testing sites nationwide, while integrating apps that not only track individuals if they have tested positive, but also warn them if they might have been exposed to a known case.

Yet in the United States and the United Kingdom, there is a public and internal government debate over whether testing matters—particularly for those who are only having minor symptoms. As of March 20, South Korea’s rate of testing was 6,148 per million people, while the United Kingdom was testing only 960 people per million and the United States just 314. Why waste resources and time trying to identify who has the disease, these officials ask.

In fact, the U.K. government even took a strategic decision on March 12 to stop testing those who have mild symptoms, those coming into hospitals but not admitted, or even the country’s health workforce. This was a dangerous and shortsighted decision, as Prime Minister Boris Johnson’s U-turn less than a week later, when he committed to a goal of 25,000 tests per day, reveals.

There are five key reasons why testing matters.

First, people generally seem much more likely to isolate themselves if they are confirmed as a virus carrier. Government advice has been for individuals to isolate themselves for 7 or 14 days (depending on the country) in order not to spread the virus beyond their household. However, this is unrealistic for those who can only earn a living by showing up at work and depend on daily income, as well as those who wonder if they really have COVID-19 or are just having another of the seasonal viruses that circulate during the winter and early spring. As with HIV, knowing one’s status can ensure that people understand the ramifications of their actions and how they need to act responsibly to prevent further spread.

Given that presymptomatic transmission accounts for a large number of cases, testing is required to ensure that carriers of the coronavirus are not unknowingly passing it on to others.

Second, to break chains of transmission, public health officials need to know where the virus is and who has been exposed to it. Given that some studies estimate that presymptomatic transmission accounts for approximately 50 percent of cases, testing is required to ensure that carriers of the coronavirus are not unknowingly passing it on to others. In addition, close contacts of virus carriers must be informed so that they isolate themselves, meaning colleagues at work, people in the same apartment building, or those who have been in the same cafes, shops, trains, or planes. This is a classic public-health technique and one of the only ways to build a robust picture of who could have possibly been exposed to the virus and be carrying it.

Third, as local authorities scramble to allocate hospitals the right amount of personal protective equipment for staff, appropriate equipment such as ventilators and oxygen and beds, and even personnel, they need to predict how many people will be arriving in intensive care units in the coming days. By testing who has COVID-19 at an early stage, and by having existing data on what percentage of these people will require further care in hospitals, officials can make these decisions based on more precise and accurate data so that resources can flow appropriately.

Fourth, as China and South Korea have shown, certain parts of a country can become hot spots with a high number of cases. This is already happening in London, given the number of people arriving in hospital who are seriously ill with COVID-19. But rather than gauging this by looking at the number of people currently requiring hospital admission—which is actually a glimpse of past community transmission—by actively testing, public health authorities could see where new hot spots are emerging , and inside those hot spots, the role of superspreading events where numerous people become infected in one place, such as during church services or eating at restaurants.

It makes a huge difference if a country has 50, 500, or 50,000 cases. Without accurate numbers, governments and doctors are trying to fight a fire without knowing how large the blaze is, or where unseen embers are burning.

Finally, the World Health Organization is producing daily reports noting the number of confirmed cases per country in order to track the evolution of the outbreak, but the accuracy of these numbers is reliant on actually doing tests. Without widespread testing of all cases including those with mild symptoms or those who are asymptomatic virus carriers, no one knows how large the problem is. It makes a huge difference if a country has 50 cases, 500 cases, or 50,000 cases, and without accurate numbers, governments and doctors are trying to fight a fire without knowing how large the blaze is, or where unseen embers are burning.

Every outbreak starts and ends with a diagnostic test. The director-general of the World Health Organization, Tedros Adhanom Ghebreyesus, has made it clear that the “backbone” of every country’s public health response to this outbreak is testing, isolation, and contact tracing—and South Korea is showing how this model ultimately pays off in reducing spread, taking pressure off health services, and keeping its death rate one of the lowest in the world.

Rather than thinking they know best, the U.S. and U.K. governments should be listening and learning from other countries and the World Health Organization, and realizing that East Asian nations are now leading the way.

Devi Sridhar is a professor and chair of global public health at the University of Edinburgh. Twitter: @devisridhar

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