SEOUL (BLOOMBERG) - Highly contagious and manifesting in some with little or no symptoms, the coronavirus has the world struggling to keep up. But when it comes to containing the epidemic, one country may be cracking the code - by doubling down on testing.

South Korea is experiencing the largest virus epidemic outside of China, where the pneumonia-causing pathogen first took root late last year. But unlike China, which locked down a province of more than 60 million people to try and stop the illness spreading, South Korea hasn't put any curbs on internal movement in place, instead testing hundreds of thousands of people everywhere from clinics to drive-through stations.

It appears to be paying off in a lower-than-average mortality rate. The outbreak is also showing signs of being largely contained in Daegu, the city about 240km south of Seoul where most of the country's more than 5,700 infections have emerged. South Korea reported that the rate of new cases dropped three days in a row.

It is an approach born out of bitter experience.

An outbreak of Middle East respiratory syndrome (Mers) in 2015 killed 38 people in South Korea, with a lack of kits to test for the Mers pathogen meaning infected patients went from hospital to hospital seeking help, spreading the virus widely.

Afterward, the country created a system to allow rapid approval of testing kits for viruses which have the potential to cause pandemics.

When the coronavirus emerged, that system allowed regulators to collaborate quickly with local biotech companies and researchers to develop testing kits based on a genetic sequence of the virus released by China in mid-January. Firms were then granted accreditation to make and sell the kits within weeks - a process that usually takes a year.

In a short space of time, South Korea has managed to test more than 140,000 people for the coronavirus, using kits with sensitivity rates of over 95 per cent, according to the director of the Korean Society for Laboratory Medicine.

That is in stark contrast to countries like its neighbour Japan and the United States, where the issues China experienced early on - with unreliable and inadequate testing resulting in thousands of infected patients not being quarantined until it was too late - are now threatening to play out.

Testing widely has meant South Korea knows where its infections are centred, and so far they've been able to keep them largely contained, with outbreaks beyond Daegu in the minority. In the capital Seoul, home to 10 million people, there have only been 103 infections.

President Moon Jae-in has cast the virus fight as a battle, saying the country is "at war", with a pathogen that has killed 3,200 people globally and sickened more than 94,000. With parliamentary elections due in April, his government is under pressure to curb the outbreak and has faced criticism for not closing the border fully to travellers from China. His administration is seizing on the country's testing apparatus as a solution.

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The emphasis on diagnosis is also being credited with helping patients get treatment early, bringing the mortality rate from the virus to under 1 per cent - below every other affected country save Singapore, where the outbreak is on a much smaller scale.

"The coronavirus is highly contagious and even those without symptoms can transmit the virus, which makes it hard to stop infection among communities," said Prof Lee Hyuk-min, director at the Korean Society for Laboratory Medicine and a professor at Yonsei Severance Hospital. "Without enough testing capabilities, the death rate will be high, as the delay worsens the damage in the lungs."

By late February, when South Korea's outbreak began to accelerate, four local companies had approval to sell kits to test for the virus. The country is now able to test more than 10,000 people a day. In neighbouring Japan, only 2,684 people in total have been tested as of March 3.

The tests can deliver results within hours, with sensitivity rates of over 90 per cent, and are relatively easy to administer. Officials in Seoul have started operating "drive-through" testing stations in three districts where people can get tested without leaving their cars.

The country is also exporting its testing kits elsewhere, including to China, Europe and Pakistan, according to the manufacturers.

Seegene Inc, a diagnostics company based in Seoul, started developing its coronavirus testing kit during the Chinese New Year holiday in late January.

"It was an adventurous investment for the company to start developing the test kit, as we weren't sure how contagious the virus would be at the time," said Park Yo-han, an investor-relations manager at Seegene. "We thought we needed to contribute to society."

The company's stock fell slightly on Thursday (March 5) after soaring 21 per cent this year on expectations its sales will grow.

While pharmaceutical giants like Roche Holding have also developed reliable coronavirus testing kits, Seegene can churn out tests more quickly using a production system automated with artificial intelligence, said Shin Jae-hoon, an analyst at Hanwha Investment & Securities Co.

The country's inroads in test kit production also reflect South Korea's position as a powerhouse for complex manufacturing, with electronic parts like memory chips and OLED displays that go into smartphones and laptops made there. The country spends more of its economic output on scientific and technological research than its most advanced rivals like Japan and Germany.

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In Hubei province, the region of China which has been devastated by the virus and is still under mass quarantine, the shortage of tests and their tendency to throw up false negatives meant that thousands of infected patients were not hospitalised before they spread the virus widely to other people.

"China used massive social distancing to respond to the outbreak, but that would be difficult to replicate in most countries and might have adverse economic consequences," said Associate Professor Ben Cowling at the School of Public Health of University of Hong Kong.

Similar issues are now cropping up elsewhere. Japan is facing criticism for a failure to test widely and well: two passengers let off a cruise ship the country locked down for weeks in Yokohama harbour to contain the virus tested positive after they returned home. Local officials from Tokyo to further-flung prefectures like Wakayama say they don't have enough test kits.

The US case tally - at 126 infections and 11 deaths - has some speculating the country just isn't testing enough. New York and Florida have complained of faulty tests and a shortage of supply, and fewer than 2,000 people have been been checked for the virus nationally as of last week.

Similar scenarios are playing out in other virus hot spots like Iran and Italy. Expanded testing will likely show that transmission within communities has been taking place for longer than realised, said Prof Raina MacIntyre, professor of infectious diseases at the University of New South Wales. "In the US, the emergence of cases with no risk factors suggests that community transmission is a serious concern," she said.

For South Korea, widespread testing has helped it get a handle on the scale of the epidemic, but once diagnosed with the virus patients need to be isolated and treated. In Daegu, hospital beds are running out and public anger is rising over a shortage of masks and other supplies.

"We are testing people on the biggest scale, at the fastest pace in the world, and disclosing the results transparently and instantly to public," Mr Moon said in a speech on Tuesday. "We believe this is the best thing we can do for now in order to prevent further spread in local communities."