Update of Guidelines for Laboratory Diagnosis of COVID-19 in Korea

Agency have announced guidelines for diagnosing coronavirus disease in clinical laboratories in Korea. With the ongoing pandemic, we propose an update of the previous guidelines based on new scientific data. This update includes recommendations for tests that were not included in the previous guidelines, including the rapid molecular test, antigen test, antibody test, and self-collected specimens, and a revision of the previous recommendations. This update will aid clinical laboratories in performing laboratory tests for diagnosing COVID-19.

# Introduction
We propose an update of the Guidelines for Laboratory Diagnosis of Coronavirus Disease in Korea issued by Korean Society for Laboratory Medicine (KSLM) and the Korea Disease Control and Prevention Agency (KDCA) that elaborate on the tests recommended for diagnosing COVID-19 [bib_ref] Guidelines for laboratory diagnosis of coronavirus disease 2019 (COVID-19) in Korea, Hong [/bib_ref]. This update includes recommendations for the rapid molecular test, antigen test, antibody test, and self-collected respiratory specimens, which were not covered in the previous guidelines, and a revision of the previous recommendations based on new scientific data [fig_ref] Table 1: Types of COVID-19 laboratory tests in Korea [/fig_ref].

## Molecular tests
KSLM and KDCA recommend real-time reverse transcription (rRT)-PCR as a molecular test for diagnosing COVID- [bib_ref] Change in saliva RT-PCR sensitivity over the course of SARS-CoV-2 infection, Congrave-Wilson [/bib_ref]. In addition to rRT-PCR, there are various isothermal amplification methods, including loop-mediated isothermal amplification and clustered regularly interspaced short palindromic repeats-based tests [bib_ref] Diagnostics for SARS-CoV-2 infections, Kevadiya [/bib_ref] [bib_ref] Diagnostic performances of common nucleic acid tests for SARS-CoV-2 in hospitals and..., Au [/bib_ref] [bib_ref] Detect and destroy: CRISPR-based technologies for the response against viruses, Freije [/bib_ref] [bib_ref] Reverse transcriptase loop mediated isothermal amplification (RT-LAMP) for COVID-19 diagnosis: a systematic..., Subali [/bib_ref] [bib_ref] The diagnostic accuracy of isothermal nucleic acid point-of-care tests for human coronaviruses:..., Subsoontorn [/bib_ref] [bib_ref] Abbott ID now COVID-19 assay performance: a year in review, Thwe [/bib_ref]. However, meta-analyses of these methods revealed insufficient performance or insufficient data; therefore, they should be used with caution in Korea at present [bib_ref] Diagnostic performances of common nucleic acid tests for SARS-CoV-2 in hospitals and..., Au [/bib_ref] [bib_ref] Detect and destroy: CRISPR-based technologies for the response against viruses, Freije [/bib_ref] [bib_ref] Reverse transcriptase loop mediated isothermal amplification (RT-LAMP) for COVID-19 diagnosis: a systematic..., Subali [/bib_ref] [bib_ref] The diagnostic accuracy of isothermal nucleic acid point-of-care tests for human coronaviruses:..., Subsoontorn [/bib_ref] [bib_ref] Abbott ID now COVID-19 assay performance: a year in review, Thwe [/bib_ref].

## Specimen types
Nasopharyngeal and oropharyngeal swabs collected simultaneously and placed in the same transport medium are no longer recommended for routine use because of the high risk of droplet generation in the process of placing two swabs in the same transport medium and because the viral loads are similar between the two specimen types; nasopharyngeal swabs are sufficient [bib_ref] SARS-CoV-2 detection in different respiratory sites: a systematic review and meta-analysis, Mohammadi [/bib_ref]. The use of an inactivating agent-containing transport medium (e.g., a chaotropic agent) for molecular tests provides safer specimen handling [bib_ref] Evaluation of chemical protocols for inactivating SARS-CoV-2 infectious samples, Pastorino [/bib_ref] [bib_ref] Analysis of inactivation of SARS-CoV-2 by specimen transport media, nucleic acid extraction..., Welch [/bib_ref].

## Self-collected respiratory specimens
KSLM and KDCA generally do not recommend using self-collected respiratory specimens for diagnosing asymptomatic patients. Studies have investigated diagnosing COVID-19 using self-collected respiratory specimens, such as saliva, anterior nasal swabs (ANS), and mouthwash, as alternatives to nasopharyngeal and oropharyngeal swabs [bib_ref] A systematic review and meta-analysis of upper airway swab collection for detection..., Harrison [/bib_ref] [bib_ref] Performance of saliva, oropharyngeal swabs, and nasal swabs for SARS-CoV-2 molecular detection:..., Lee [/bib_ref] [bib_ref] Comparison of saliva and nasopharyngeal swab nucleic acid amplification testing for detection..., Butler-Laporte [/bib_ref] [bib_ref] The sensitivity and costs of testing for SARS-CoV-2 infection with saliva versus..., Bastos [/bib_ref]. The advantage of these specimens is that they are easily obtained. However, recent prospective studies have revealed that the test sensitivities for saliva and ANS in asymptomatic patients were significantly lower than those for nasopharyngeal swabs [bib_ref] Prospective comparison of saliva and nasopharyngeal swab sampling for mass screening for..., Nacher [/bib_ref] [bib_ref] Clinical evaluation of self-collected saliva by quantitative reverse transcription-PCR (RT-qPCR), direct RT-qPCR,..., Nagura-Ikeda [/bib_ref] [bib_ref] Effects of patient characteristics on diagnostic performance of self-collected samples for SARS-CoV-2..., Smith-Jeffcoat [/bib_ref] [bib_ref] Change in saliva RT-PCR sensitivity over the course of SARS-CoV-2 infection, Congrave-Wilson [/bib_ref]. In addition, pooled tests using saliva or ANS have lower sensitivities than individual tests using saliva or ANS [bib_ref] Testing individual and pooled saliva samples for sars-cov-2 nucleic acid: a prospective..., Migueres [/bib_ref] [bib_ref] Pooled saliva specimens for SARS-CoV-2 testing, Barat [/bib_ref] [bib_ref] Comparison of three commercial SARS-CoV-2 assays for pooled testing of deep throat..., Ho [/bib_ref] [bib_ref] Evaluation of sample pooling for SARS-CoV-2 RNA detection in nasopharyngeal swabs and..., Mcmillen [/bib_ref]. Therefore, collecting such specimens can be considered for patients who need repeated specimen collection or in whom nasopharyngeal swabs are difficult to collect. However, the possibility of false negatives should be carefully considered in advance [bib_ref] Infectious Diseases Society of America guidelines on the diagnosis of COVID-19, Hanson [/bib_ref] [bib_ref] The Infectious Diseases Society of America guidelines on the diagnosis of COVID-19:..., Hanson [/bib_ref]. The possibility of viral transmission during the process of self-collection should also be considered.

## Test interpretation
KSLM and KDCA recommend using a molecular test that targets two or more sites of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome and to consider a CO-VID-19 diagnostic test positive only when all targets are positive. If the initial test result is inconclusive in a patient with no history of confirmed COVID-19, collecting a new specimen for retesting is recommended.
The following criteria apply only to the newly confirmed CO-VID-19 cases and in the course of treatment of a patient with confirmed COVID-19. The rRT-PCR test result can be judged The false-negative rate is high in pre-symptomatic or asymptomatic patients. The false-positive rate is high when prevalence is low.

## Antibody test confirmation of past infection or multisystem inflammation syndrome or serosurveillance
Assays with high specificity should be used. Not recommended for evaluating the risk of infection.

## Considerations for test interpretation
Molecular tests that target a single site are not recommended for diagnosing COVID-19 as various mutations affecting test sensitivity have been reported [bib_ref] A recurrent mutation at position 26340 of SARS-CoV-2 is associated with failure..., Artesi [/bib_ref] [bib_ref] SARS-CoV-2 samples may escape detection because of a single point mutation in..., Ziegler [/bib_ref] [bib_ref] Prevalence of a single-nucleotide variant of SARS-CoV-2 in Korea and its impact..., Hong [/bib_ref] [bib_ref] Identification of a polymorphism in the N gene of SARS-CoV-2 that adversely..., Vanaerschot [/bib_ref] [bib_ref] Endemic SARS-CoV-2 polymorphisms can cause a higher diagnostic target failure rate than..., Rhoads [/bib_ref] [bib_ref] A needle in the haystack? Assessing the significance of envelope (E) gene-negative,..., Khoshchehreh [/bib_ref] [bib_ref] SARS-CoV-2 E gene variant alters analytical sensitivity characteristics of viral detection using..., Tahan [/bib_ref] [bib_ref] Twostep strategy for the identification of SARS-CoV-2 variant of concern 202012/01 and..., Bal [/bib_ref] [bib_ref] Tracking SARS-CoV-2 lineage B.1.1.7 dissemination: insights from nationwide spike gene target failure..., Borges [/bib_ref]. Multiple targets can also discriminate non-specific reactions, background fluorescence signals, and cross-reactivity, which can cause false-positive results [bib_ref] Cautionary note on contamination of reagents used for molecular detection of SARS-CoV-2, Huggett [/bib_ref] [bib_ref] DNA cross-reactivity of the CDC-specified SARS-CoV-2 specimen control leads to potential for..., Rosebrock [/bib_ref] [bib_ref] False positive results with SARS-CoV-2 RT-PCR tests and how to evaluate a..., Braunstein [/bib_ref]. The targets do not necessarily have to be located in different genes. Some reagents target multiple sites but employ the same fluorescent dyes; in such cases, the manufacturer has to establish a method to differentiate between non-specific reaction and SARS-CoV-2 genome amplification for the user.

## Solutions for inconclusive results
If the results are inconsistent after retesting, they can be judged false positive, and when the results are consistent, the results can be judged positive. If there is a possibility of cross-contamination, re-amplification of the extracted nucleic acids is not sufficient; the specimen must be re-extracted or a new specimen must be collected. The possibility of COVID-19 can be judged by reviewing the patient's medical history. In some cases, an antibody test may help in interpreting inconsistent or inconclusive results. To determine the risk of cross-contamination, it is recommended to follow-up the laboratory's positive-test rate or to consider the location of other SARS-CoV-2-positive specimens on the PCR plate [bib_ref] COV-ID-19 molecular testing in Korea: practical essentials and answers from experts based..., Sung [/bib_ref].

# Result reporting
KSLM and KDCA do not recommend routine reporting of threshold cycle (Ct) values [bib_ref] AACC practical recommendations for implementing and interpreting SARS-CoV-2 EUA and LDT serologic..., Zhang [/bib_ref] [bib_ref] The dangers of using Cq to quantify nucleic acid in biological samples:..., Evans [/bib_ref]. All currently approved COVID-19 molecular tests are qualitative tests. Respiratory specimens are not homogeneous in quality and the amount collected, and there are differences between reagents used, leading to large fluctuations in Ct values. In external quality programs of COVID-19 molecular tests conducted in Korea and other countries, a very wide range of Ct values [bib_ref] Analysis of inactivation of SARS-CoV-2 by specimen transport media, nucleic acid extraction..., Welch [/bib_ref] [bib_ref] A systematic review and meta-analysis of upper airway swab collection for detection..., Harrison [/bib_ref] [bib_ref] Performance of saliva, oropharyngeal swabs, and nasal swabs for SARS-CoV-2 molecular detection:..., Lee [/bib_ref] [bib_ref] Comparison of saliva and nasopharyngeal swab nucleic acid amplification testing for detection..., Butler-Laporte [/bib_ref] [bib_ref] The sensitivity and costs of testing for SARS-CoV-2 infection with saliva versus..., Bastos [/bib_ref] [bib_ref] Prospective comparison of saliva and nasopharyngeal swab sampling for mass screening for..., Nacher [/bib_ref] [bib_ref] Clinical evaluation of self-collected saliva by quantitative reverse transcription-PCR (RT-qPCR), direct RT-qPCR,..., Nagura-Ikeda [/bib_ref] [bib_ref] Effects of patient characteristics on diagnostic performance of self-collected samples for SARS-CoV-2..., Smith-Jeffcoat [/bib_ref] [bib_ref] Change in saliva RT-PCR sensitivity over the course of SARS-CoV-2 infection, Congrave-Wilson [/bib_ref] [bib_ref] Testing individual and pooled saliva samples for sars-cov-2 nucleic acid: a prospective..., Migueres [/bib_ref] [bib_ref] Pooled saliva specimens for SARS-CoV-2 testing, Barat [/bib_ref] [bib_ref] Comparison of three commercial SARS-CoV-2 assays for pooled testing of deep throat..., Ho [/bib_ref] [bib_ref] Evaluation of sample pooling for SARS-CoV-2 RNA detection in nasopharyngeal swabs and..., Mcmillen [/bib_ref] [bib_ref] Infectious Diseases Society of America guidelines on the diagnosis of COVID-19, Hanson [/bib_ref] [bib_ref] The Infectious Diseases Society of America guidelines on the diagnosis of COVID-19:..., Hanson [/bib_ref] [bib_ref] A recurrent mutation at position 26340 of SARS-CoV-2 is associated with failure..., Artesi [/bib_ref] has been observed [bib_ref] Variability of cycle threshold values in an external quality assessment scheme for..., Buchta [/bib_ref] [bib_ref] Variable sensitivity of SARS-CoV-2 molecular detection in European expert laboratories: external quality..., Fischer [/bib_ref] [bib_ref] Nationwide external quality assessment of SARS-CoV-2 molecular testing, Sung [/bib_ref] [bib_ref] International external quality assessment for SARS-CoV-2 molecular detection and survey on clinical..., Matheeussen [/bib_ref]. Making clinical judgments, e.g., on quarantine release, based on Ct values has a high probability of error [bib_ref] The dangers of using Cq to quantify nucleic acid in biological samples:..., Evans [/bib_ref] [bib_ref] Challenges and controversies to testing for COVID-19, Binnicker [/bib_ref] [bib_ref] Can testing predict SARS-CoV-2 infectivity? The potential for certain methods to be..., Binnicker [/bib_ref]. Ct values should be interpreted cautiously in consultation with the laboratory director.

## Pooled test using rrt-pcr
KSLM and KDCA recommend that test performance must be verified before using in the pooled specimen test method for the screening of asymptomatic patients [bib_ref] AACC practical recommendations for implementing and interpreting SARS-CoV-2 EUA and LDT serologic..., Zhang [/bib_ref] [bib_ref] Pooling upper respiratory specimens for rapid mass screening of COVID-19 by realtime..., Kim [/bib_ref]. The pooled rRT-PCR test for COVID-19 uses pooled upper respiratory tract specimens for the screening of asymptomatic patients with COVID-19 [bib_ref] Pooling upper respiratory specimens for rapid mass screening of COVID-19 by realtime..., Kim [/bib_ref] [bib_ref] Evaluation of COVID-19 RT-qPCR test in multi sample pools, Yelin [/bib_ref] [bib_ref] Upper respiratory samples pooling for screening SARS-CoV-2 infection: ready for the prime..., Lippi [/bib_ref]. If the pooled test result is positive, all specimens included in the pooled test are subjected to rRT-PCR individually for confirmation. This method cannot be used for confirming suspected COVID-19 and should be limited to the screening of asymptomatic patients. For suspected patients, rRT-PCR of individual specimens is recommended.
As the pooled specimen test method is a screening test, sensitivity should be maintained as high as possible; the possibility of a decrease in sensitivity should be considered [bib_ref] Upper respiratory samples pooling for screening SARS-CoV-2 infection: ready for the prime..., Lippi [/bib_ref] [bib_ref] Challenges and issues of SARS-CoV-2 pool testing, Lee [/bib_ref]. Sensitivity may vary with the transport medium, nucleic acid extraction method, and PCR reagent used and the pool size [bib_ref] Performance of nucleic acid amplification tests for detection of severe acute respiratory..., Wang [/bib_ref] [bib_ref] Evaluation of seven commercial RT-PCR kits for COVID-19 testing in pooled clinical..., Garg [/bib_ref]. Therefore, it is necessary to verify whether the pooled specimen test method can be applied to the conditions used in each laboratory before testing.
-For general matters and considerations, refer to the previous guidelines and the protocol of KSLM for the pooled specimen test method [bib_ref] Pooling upper respiratory specimens for rapid mass screening of COVID-19 by realtime..., Kim [/bib_ref]. -Regarding the determination of the pool size, various factors should be considered, including the virus amount of the newly diagnosed patient, the nucleic acid extraction method used, and the performance of the PCR reagent. Generally, a pool of no more than five to six specimens is recommended. -Before starting a new test or changing the test method, a combination of the nucleic acid extraction method and PCR reagent should be tested with sufficient positive specimens to confirm that 100% sensitivity is obtained for the pooled test. In the verification process, sufficient specimens with high Ct values (e.g., at least 30% specimens with a Ct value  30) should be used. These recommendations are based on the distribution of the Ct values of newly diagnosed cases in Korea [bib_ref] Pooling upper respiratory specimens for rapid mass screening of COVID-19 by realtime..., Kim [/bib_ref] [bib_ref] Clinical performance of the Standard Q COVID-19 Rapid Antigen Test and simulation..., Lee [/bib_ref].

## Rapid molecular test
KSLM and KDCA recommend using reagents and equipment with verified performance when using a rapid molecular test [bib_ref] IFCC interim guidelines on molecular testing of SARS-CoV-2 infection, Bohn [/bib_ref]. The rapid molecular test for COVID-19 is used for the confirmation of a COVID-19 diagnosis within a short time [bib_ref] Rapid, point-of-care antigen and molecular-based tests for diagnosis of SARS-CoV-2 infection, Dinnes [/bib_ref]. Considering the performance of the currently available rapid molecular tests and the prevalence of COVID-19 in Korea, a rapid molecular test should be used only for screening, and positive specimens should be confirmed using a validated rRT-PCR test. A rapid molecular test is not recommended for the pooled specimen method, which requires maximum sensitivity. Rapid molecular tests that employ a general thermocycler and rRT-PCR reagent with a short reaction time are not suitable for emergency situations as not all processes are automated and the equipment is not suitable for detecting short-time reactions.

## Test procedure
As most rapid molecular tests do not use positive and negative controls, an internal control must be included in the same reaction well as the specimen.
Before using the rapid molecular test, it is recommended to verify its performance with sufficient positive specimens to confirm that 100% sensitivity is obtained for multiple pooled specimens. In the verification process, it is recommended to include sufficient specimens with high Ct values (e.g., at least 30% of specimens with a Ct value  30). These recommendations are based on the distribution of Ct values of newly reported cases in Korea [bib_ref] Pooling upper respiratory specimens for rapid mass screening of COVID-19 by realtime..., Kim [/bib_ref] [bib_ref] Clinical performance of the Standard Q COVID-19 Rapid Antigen Test and simulation..., Lee [/bib_ref].

## Interpretation
Even if only one of the target genes is present, it is considered presumptive positive, and a validated rRT-PCR test is recommended for confirmation. As rapid molecular tests are for screening, inconclusive results should be considered presumptive positive. The positive predictive value may be low when the prevalence is low as the specificity of the rapid molecular test is not sufficiently high. In such a case, both positive and inconclusive rapid molecular test results should be considered only as screening test results and the results should be confirmed using a conventional rRT-PCR test.

## Antigen test
KSLM and KDCA do not recommend using a SARS-CoV-2 antigen test for asymptomatic individuals. Considering the low sensitivity and specificity of the antigen tests and the relatively low prevalence of COVID-19 in Korea, SARS-CoV-2 antigen tests have a very limited role in the screening of asymptomatic patients in Korea [bib_ref] Clinical performance of the Standard Q COVID-19 Rapid Antigen Test and simulation..., Lee [/bib_ref] [bib_ref] The Infectious Diseases Society of America guidelines on the diagnosis of COVID-19:..., Hanson [/bib_ref] [bib_ref] Performance of an antigen-based test for asymptomatic and symptomatic SARS-CoV-2 testing at..., Pray [/bib_ref] [bib_ref] Clinical application of the Standard Q COVID-19 Ag Test for the detection..., Oh [/bib_ref] [bib_ref] Diagnostic performance of an antigen test with RT-PCR for the detection of..., Brihn [/bib_ref]. The European Centers for Disease Control and Prevention recommend that antigen tests should not be used for the screening of asymptomatic patients if the prevalence is < 10%. The sensitivity of antigen tests using self-collected specimens, such as saliva or ANS, is even lower [bib_ref] Diagnostic performance of an antigen test with RT-PCR for the detection of..., Brihn [/bib_ref] [bib_ref] Validation testing to determine the sensitivity of lateral flow testing for asymptomatic..., Ferguson [/bib_ref] [bib_ref] Point-of-care antigen test for SARS-CoV-2 in asymptomatic college students, Tinker [/bib_ref] [bib_ref] Performance of the Innova SARS-CoV-2 antigen rapid lateral flow test in the..., Garcia-Finana [/bib_ref] [bib_ref] Epidemiologic characteristics associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen-based..., Ford [/bib_ref].
The use of a SARS-CoV-2 antigen test may be considered for symptomatic patients within seven days from symptom onset (1) when the prevalence and positive predictive value are high, [bib_ref] Diagnostics for SARS-CoV-2 infections, Kevadiya [/bib_ref] when the molecular test results are delayed for more than 48 hrs, and (3) when effective prophylactic treatment can be administered on the basis of clinical suspicion even after suspected false-negative results with the antigen test. A molecular test is recommended simultaneously with the antigen test to reduce the possibility of false positives or false negatives [bib_ref] Implementation of rapid SARS-CoV-2 antigenic testing in a laboratory without access to..., Blairon [/bib_ref]. The manufacturer's instructions for immunochromatography must be followed strictly as result interpretation may be subjective [bib_ref] Evaluation of SARS-CoV-2 serology assays reveals a range of test performance, Whitman [/bib_ref].

## Antibody test
KSLM and KDCA do not recommend using an antibody test for diagnosing acute COVID-19 or for evaluating the risk of infection for individuals who have recovered from COVID-19 or who have been vaccinated for COVID-19 [bib_ref] AACC practical recommendations for implementing and interpreting SARS-CoV-2 EUA and LDT serologic..., Zhang [/bib_ref] [bib_ref] European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for..., Ong [/bib_ref] [bib_ref] The role of antibody testing for SARS-CoV-2: is there one?, Theel [/bib_ref]. SARS-CoV-2 antibody tests are indicated (1) for serosurveillance studies, [bib_ref] Diagnostics for SARS-CoV-2 infections, Kevadiya [/bib_ref] in the case of strong suspicion of past SARS-CoV-2 infection based on epidemiological and clinical results and repeated negative or indeterminate molecular tests, (3) in the case of suspected CO-VID-19-related multisystem inflammatory syndrome, (4) for the selection of convalescent plasma donors from patients who have recovered from COVID-19 for therapeutic purposes, (5) for studies aimed at investigating the efficacy or effectiveness of a vaccine, and (6) for entry into a country where a SARS-CoV-2 antibody test result is a prerequisite. An antibody test with very high specificity (e.g.,  99.5%) should be used [bib_ref] Infectious Diseases Society of America guidelines on the diagnosis of COVID-19: serologic..., Hanson [/bib_ref] [bib_ref] Performance Comparison of Five SARS-CoV-2 Antibody Assays for Seroprevalence Studies, Park [/bib_ref] [bib_ref] Comparison of SARS-CoV-2 Antibody Responses and Seroconversion in COVID-19 Patients Using Twelve..., Yun [/bib_ref]. To diagnose a breakthrough infection in a vaccinated patient, an antibody test detecting antigens not targeted by the vaccine received should be used.

## Laboratory guidelines for biosafety and infection control
KSLM and KDCA recommend that only fully COVID-19-vaccinated healthcare personnel perform the tests [bib_ref] Laboratory biosafety measures involving SARS-CoV-2 and the classification as a Risk Group..., Kaufer [/bib_ref] [bib_ref] SARS-CoV-2 Working Group. Detection of SARS-CoV-2 on high-touch surfaces in a clinical..., Bloise [/bib_ref] [bib_ref] Comprehensive analyses of SARS-CoV-2 transmission in a public health virology laboratory, Zuckerman [/bib_ref].

## Acknowledgements
None.

# Author contributions
Hong KH and Kim GJ reviewed the literature on the currently used general recommendations and wrote the manuscript. Roh KH and Sung H contributed to general concepts and recommendations. Lee J and Kim SY contributed to recommendations for antigen tests, pooling tests, and rapid molecular tests. Kim TS and Kim J-S contributed to recommendations for biosafety. Park Y and Kim HS contributed to recommendations for antibody testing. Park J-S, Huh HJ, Seong M-W, and Ryoo N collated protocols and interpreted results and contributed to recommendations. Lee H, Song SH, Kwon GC, and Yoo CK organized the task force and contributed to the concept and design of the guidelines.

## Conflicts of interest
None.

# Research funding
None declared.

## Orcid
[table] Table 1: Types of COVID-19 laboratory tests in Korea [/table]