It is well-known that South-Korea has developed a powerful system of drive-through testing allowing them to test hundreds of thousands of person in the past two months. I was wondering whether the test-subjects all visit those testing stations on a voluntary basis (because they are worried about their health) or whether true random samples of the population are being tested, supposedly requiring a government order to have certain people take a test on a (semi)compulsory basis.

To summarize: Is SK conducting random covid-19 tests on sizeable random samples of its population? Is any other country with a major outbreak doing such a thing?

This question arose in my mind in the light of rumours that the covid-19 epidemic would have a tendency to create a pool of infected 10 times larger than reported because alledgedly the main bulk of the infected don't experience grave symptoms and do not seek out a test or diagnosis.

  • The "10 times higher" source you linked is talking about government suppression of case numbers, not about lack of symptoms. The number of infected who lack symptoms has been variously reported in the range of 25% to 60% depending on the specific study (and that range is not too surprising given the differing population characteristics). Please read news carefully before theorizing about it.
    – Bryan Krause
    Commented Apr 3, 2020 at 16:30
  • The lacking of symptoms is not a rumor, it's the result of scientific studies (and is on topic here). The issue of government underreporting is more of a rumor, depending on how much you trust intelligence reports publicized by other governments, but in any case is not on-topic here because it's not about medical sciences but about politics.
    – Bryan Krause
    Commented Apr 3, 2020 at 16:35
  • No, no, my question is about random testing in SK: is that not on-topic? A factual objective answer should be easy to get for the right person?
    – 5th decile
    Commented Apr 3, 2020 at 16:37
  • I'll modify my question to stress that I'm asking about random testing in SK.
    – 5th decile
    Commented Apr 3, 2020 at 16:37

2 Answers 2


Is SK conducting random covid-19 tests on sizeable random samples of its population?

Not currently (source: South Korean friends).

Is any other country with a major outbreak doing such a thing?

See Why don't we take a random sample of the population to estimate the amount of COVID-19 cases?

  • 1
    "source: South Korean friends" ahaha :) Commented Apr 3, 2020 at 20:57
  • 1
    Hearsay is also useful: often, when something has not been done there is no literature about it.
    – 5th decile
    Commented Apr 3, 2020 at 21:00
  • @ThibautDemaerel yep, not to mention one of them is a physician working in Seoul. I was told to get free testing one must have been exposed to a contaminated individual (maybe there is a some other way to get free tests, e.g. used to be the case for some inbound international air travelers I believe, but we can't just walk in in a testing facility and get a free test). Commented Apr 3, 2020 at 21:04
  • 1
    A CNN article from Mar 3rd (edition.cnn.com/2020/03/02/asia/…) says: "Health workers screen visitors with a questionnaire about their travel history and symptoms. Only those deemed to be at-risk will be tested." Also, en.wikipedia.org/wiki/… indicates that 8.5 per 1000 inhabitants are SARS-CoV-2-positive, but 23 out of 1000 tests are positive, which is further evidence towards testing higher risk sub-pobulations. Commented Apr 3, 2020 at 21:34
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    @cbeleitesunhappywithSX thanks for the references! Commented Apr 3, 2020 at 21:59

South Korea has adopted a highly technical and transparent approach to Covid-19. By sharing where infected people have been, citizens can see if they have been in contact or near contact with the infected person, and then request a test.

Since the first cases were confirmed, Korean public health authorities and local governments collaborated to precisely document the movement of infected people down to the minute. Authorities sought testimony, watched closed-circuit television, investigated smartphone GPS data and more, publicizing the so-called moving histories of Covid-19 patients. All local governments share information through websites, text messages, and media. Companies have developed apps that allow users to visualize the information. Koreans can now learn where infected people went, when they were there, and how they got there. If someone learns they might have been exposed, they can quickly visit a doctor and begin self-quarantine if they have similar symptoms.

On February 4, the Korea Centers for Disease Control and Prevention took advantage of the post-MERS reform and authorized an unlicensed Covid-19 test; the government went on to test an extraordinary number of people. By February 26, Korea had tested 46,127 cases, while by that point, Japan had tested just 1,846 cases and the United States only 426. Tests still remain hard to come by in the United States, despite the Trump administration’s repeated suggestions that widespread testing is imminent.

There are few countries as technologically advanced as South Korea that are able to adopt this approach without a wide spread lockdown. And it helped that they allowed the use of an unapproved tests whereas in the USA the CDC blocked the use of independent tests which has lead to their current deplorable state of testing.

Following the end of the MERS outbreak, South Korea enacted a new law in 2016 that allows laboratories to use unapproved in-vitro diagnostic kits in the case of a public health emergency.


“Testing is absolutely critical with a fast-travelling virus like this,” says Kang. “We have tested over 350,000 cases so far – some patients are tested many times before they are released, so we can say they are fully cured. Altogether, we’re talking about one out of 145 or one out of 150 people having been tested so far.”



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