Up until 2 months ago, no one knew about the infectious disease caused by the novel coronavirus (COVID-19). Clusters of patients with an unknown form of pneumonia were reported on December 31st of last year and the cause of these cases was later determined to be COVID-19. In South Korea, the first confirmed case of COVID-19 was reported on January 20th, 2020.
With the coronavirus proliferating rapidly in different parts of the world, the entire world is in need to develop diagnostic tests. While monitoring the situation in China, the Korean preventive epidemiology authority started to prepare before COVID-19 entered the country. On January 13th, the Korean Center for Disease Control (KCDC) announced was ready to launch the development of the COVID-19 diagnostic tools. The newly developed diagnostic kits were distributed to about 50 private hospitals equipped with testing facilities starting on February 7th. The widespread distribution of test kits facilitated and accelerated the screening process to detect COVID-19 positive cases, since previously, only KCDC and 18 city and provincial health institutes were able to conduct the tests. As COVID-19 spread to the Korean community and the confirmed cases were reported from countries other than China, it became more important to have many local sites performing the tests.
How did Korea develop the diagnostic test even before the virus was fully characterized? In the early stage of the spread, there were no testing tools that could detect COVID-19 specifically. Up until January 30th, KCDC confirmed the cases with a ‘pan-coronavirus test’. This was done by testing whether the patient was positive for coronaviruses and, then, excluding other known types of coronaviruses. There were a total 6 different kinds of known coronaviruses including SARS and MERS. If the genetic sequence of the virus did not match any of these 6 virus sequences, it was diagnosed as a novel coronavirus. The pan-coronavirus test took 1-2 days since it had to go through this 2-step process.
By January 31st, testing methods became significantly simpler by introducing the rRT-PCR (real time reverse transcriptase polymerase chain reaction) specifically for COVID-19, which can detect COVID-19 in 6 hours. PCR amplifies target sequences from the viral genome and has been widely used in the medical field, including to test for MERS.
However, to use PCR to test for COVID-19, special diagnostic reagents were necessary. The essential reagents were ‘primers’, which bind to a specific gene of COVID-19. These primers have to bind in order for the PCR reaction to amplify the viral gene. If the amplification happens sufficiently and reaches a certain threshold value, after mixing with reagents and running PCR machine, the specimen is determined to have COVID-19 and diagnosed positive. Otherwise, it is reported as negative.
Adjustment of WHO testing methods to South Korea
In order to discriminate COVID-19 from other coronaviruses using PCR, suitable diagnostic reagents had to be developed. When COVID-19 specific genetic sequences was announced, multiple counties started to develop these reagents. On January 17th, 2020, the World Health Organization (WHO) announced testing guidelines. KCDC modified this testing guideline to better fit South Korea. This process made it possible for the Korean government to determine who was infected and transfer Koreans from Wuhan using the charter planes.
Succeeding in developing diagnostic kits (reagents) did not necessarily mean that these could be distributed to front-line hospitals. The manufacturing company that could produce testing kits had to be selected and the hospitals that could perform the tests accurately had to be identified. Credibility of the testing was essential. More importantly, accurate diagnostic tests had to be deployed quickly enough to match the speed of the spread of the virus. The preventive epidemiology authority made this possible in only 17 days after the first confirmed case. Professor Lee Hyuk-Min (Yonsei University Medical School, Department of clinical diagnosis) said that “the PCR method has been used worldwide but mass production of diagnostic kits takes a long time after establishing the testing method. A system that can perform the test has never been accomplished in the private sector in such a short time period”.
The MERS outbreak in 2015 was a bitter but helpful experience. At that time, KCDC prepared for a possible outbreak and developed the testing kits in advance. However, the amount of kits was not enough to deal with the tremendous spread of the MERS virus. The Korean National Institute of Health (KNIH), a division of KCDC, was overloaded with samples to test and this delayed the diagnostic process by weeks. Fast testing and diagnosis is essential to the prevention of infectious disease spread. Professor Hwang Seung-Sik (Seoul National University, Graduate school of Public Health) said “Fast diagnosis followed by epidemiological investigation of confirmed case is a key to prevent further spread of infection”.
After this, the KCDC reorganized the system for the prevention of epidemics and made it possible to mass produce the diagnostic kits in a timely manner in case an infectious disease crisis developed. Accordingly, ‘Urgent Use Approval System’ was introduced in 2017. In order for private sector companies to make new reagents and use them, it usually took 1 year. The Urgent Use Approval System facilitates the temporal approval of processes for manufacturing, marketing, and using new diagnostic reagents. This can happen upon request of the director of KCDC to Ministry of Food and Drug Safety when infectious disease is expected. Testing kits manufactured by Kogene Biotech, a private reagent manufacturer, were approved for urgent use on February 4th and these kits were used at front-line hospitals from February 7th.
The KCDC newly founded the Center for Laboratory Control of Infectious Disease to regulate the diagnostic tests for infectious diseases in 2017. Under this center, a division of Laboratory Diagnosis Management has been continuously cooperating with private professional groups such as the Korean Society for Laboratory Medicine. With this new structure and the private sector’s capabilities, testing methods were developed, diagnostic kits were manufactured and testing was expanded to medical institutions quickly when the COVID-19 crisis occurred.
Hospitals validated the new COVID-19 tests on February 5th and 6th, and then started to provide COVID-19 testing from February 7th. The Korean Association of External Quality Assessment Service, a private professional association, was in charge of sending out testing specimens and diagnostic kits to each medical institution. Kwon Gye-Cheol (CEO of Korean Society for Laboratory Medicine, Chungnam National University, Department of Laboratory Medicine) said, “The COVID-19 testing process was able to be accelerated because of divided responsibilities of KCDC and the private sector and their cooperation, based on our experience with MERS.”
The scope of subjects with suspected CVID-19 who are able to receive testeds has been widened. From February 7th, anyone who came from China and other countries with fever, respiratory symptoms, or pneumonia of unknown origin have been categorized as suspected patients and are able to be tested with a doctor’s referral. Jung Eun-Kyeong, the director of the KCDC, said “Because we are planning to expand the case definition, (increasing the diagnostic testing capacity) has been pushed forward to match this plan”.
By testing more, it is possible to create a steep increase in the number of confirmed cases. Professor Lee Hyuk-Min warned, “As testing kits are distributed to additional communities and testing becomes more widespread, unexpected patients may show up. At that moment, people may get anxious but must see this optimistically since we are identifying asymptomatic infections.”
Observation of laboratory testing sites
Diagnostic testing starts with sampling specimens from a person who may be infected. Specimens are obtained from both upper respiratory (nose, mouth, airway, and etc.) and lower respiratory (lung) tracts. For the upper respiratory specimen, using a long, flexible cotton tip, mucus from the back of the nose is obtained. Sputum is used for lower respiratory specimen. In the case of the 8th and 20th confirmed cases, their tests were negative at first but they changed to positive when re-tested. This may have been due to insufficient virus in the specimen because during the latency period, the virus has not spread out to the entire body.
The method of COVID-19 testing is different from a pregnancy test or quick influenza testing kit. The laboratory of the medical institution has to have a PCR machine in a suitable facility with proper protective gear so that there is no contamination and infection within the laboratory. 〈Sisa IN〉 visited the laboratory at Seoul National University, Department of Laboratory Medicine, one of the testing laboratories that had been performing the diagnostic test using the testing kits distributed from February 7th.
Triple wrapped specimens are transferred to the laboratory. For testing, genetic material (nucleic acid) has to be extracted from the specimen. Medical laboratory technicians with personal protective equipment extract nucleic acids in a negative pressure room. This is necessary because there is a risk of infecting laboratory personnel during this process. It takes about 1.5 hours to extract.
Reagents are added to the extracted nucleic acid and the samples is are run in a PCR machine. Two COVID-19 specific genes, N and RdRP, are amplified. A laboratory medicine professional doctor who participated in developing the testing method explained that, “Coronavirus mutates easily. If the targeted gene mutates, there will be problems with the diagnosis. Therefore, genes that are less likely to be mutated were chosen as target genes.”
Up to 48 specimens can be tested in one time run of a PCR machine. Seoul National University testing laboratory has 4 PCR machines and they can run 2 to 3 times a day. Including the time for analysis and reporting the result, it takes about 6 hours for obtaining the specimen to the completion of the diagnosis.
translated by Eunjoo Lancaster
translation supervised by Beckhee Cho
