Among the many countries in the world where COVID-19 outbreaks have occurred, Korean policies concerning immigration restrictions and bans are the least restrictive. Currently, South Korea enforces immigration bans only for passengers who possess Chinese passports issued by Hubei Province, all foreigners who have visited Hubei within the past 14 days, and passengers of the anchored cruise ship (Diamond Princess) at Yokohama Port in Japan. Moreover, guidelines for passengers arriving from China have been changed to mandate a visa for transfers via Korea. The visa-exemption entry of Japanese passport holders was restricted, and the validity of all previously issued visas was suspended. For all passengers arriving in Korea from different parts of the world, entry is allowed under conditions that these foreign nationals submit a special in-flight quarantine health status report and install a mobile app for COVID-19 self-diagnosis that provides a daily report of their health status for 14 days. Since March 22 and 25, 2020, the Korean government has been conducting COVID-19 diagnostic tests for every inbound traveler entering the country from Europe and the United states, respectively. On the first day of conducting these diagnostic tests, 1444 individuals underwent the tests and 19 of them were confirmed to have COVID-19 [8].

The Korean government’s policy against COVID-19 was to invest as many medical resources as possible for screening and early diagnosis of disease [9]. This is important because isolating and monitoring patients with confirmed COVID-19 in early stages of the disease can impede further disease transmission and enable patients to be transferred to the hospital soon after they show severe respiratory symptoms, thereby reducing mortality and morbidity.

On February 7, 2020, the Korean government approved test kits that could produce results in 6 hours; thereafter, supply of the diagnostic test kits increased from 200 to 3000, and the number of screening clinics increased from 288 to 556 [10]. By February 26, South Korea had tested 46,127 individuals, while at that timepoint, Japan had tested only 1846 individuals and the United States has tested only 426 individuals [11]. South Korea continued to perform a higher number of screening tests than most other countries, with 2,322,999 tests conducted until October 1, 2020 [6].

To prevent hospitals from being overwhelmed, the Korean government opened more than 600 testing centers designed to screen as many people as quickly as possible and to keep health workers safe by minimizing contact. The government also introduced drive-through screening clinics in February. At that time, these clinics were operational in more than 50 locations nationwide, which helped minimize contact between medical staff and individuals undergoing tests and thus reduce cross-contamination and test administration time (from almost 1 hour to only about 10 minutes). These drive-through testing clinics allowed more than 15,000 COVID-19 laboratory tests to be conducted per day [9]. At some walk-in centers, patients enter a chamber resembling a transparent phone booth, wherein health care workers administer throat swabs using thick rubber gloves built into the chamber’s walls.

COVID-19 suspected cases are confirmed only by laboratory tests, using any of the following pathogenic detection criteria: (1) a positive test for SARS-CoV-2 based on respiratory or serum specimen examined by real-time reverse transcription polymerase chain reaction or (2) full genome sequences of the virus isolated from the respiratory or serum specimen are identical to SARS-CoV-2 genome sequences [12]. Patients who undergo laboratory diagnostic tests are classified into 2 groups: The first group “patients with suspected COVID-19” comprises those who have been in contact with a patient with confirmed COVID-19 within the last 14 days and have symptoms of fever over 37.5℃ or respiratory symptoms (including cough, dyspnea, and acute respiratory distress syndrome); these patients are prioritized among those who are eligible for laboratory examination [12]. The second group “patients under investigation” comprises those who have visited countries with a high incidence of COVID-19, such as China, Hong Kong, and Macao within the last 14 days or those who are epidemiologically related to the domestic outbreak and show COVID-19–related symptoms; these patients take priority after the suspected patients [12]. Those who have unexplainable pneumonia and are suspected to have COVID-19 according to the doctor’s opinion are also classified as patients under investigation and can receive diagnostic tests, even if they do not have a history of exposure to patients with confirmed COVID-19 [12]. In addition, individuals who have been in contact with patients with COVID-19 may be tested for the purpose of releasing them from quarantine even if they have no symptoms, and some of them may be identified as asymptomatic patients [12].

In the beginning, the diagnostic criteria were so strict that only a few people could receive diagnostic tests, which resulted in many patients having diseases with an unclear diagnosis. Some COVID-19 cases were confirmed without a history of exposure to patients with confirmed infection or travel within high-risk countries, or expression of any clinical symptoms; therefore, on February 16, 2020, the government decided to expand the range of patients that could receive a diagnostic examination considering the high risk of human-to-human COVID-19 transmission due to asymptomatic patients [6].

COVID-19 contact investigation and management involved the following aspects: (1) determination of the location of the contact (patient route), (2) exposure risk evaluation, (3) contact classification, and (4) contact management [9]. Exposed individuals (hereafter, contacts) need continuous monitoring regardless of whether they exhibit symptoms. The range of contact is determined by the local city and provincial response teams who evaluate the symptoms of patients with confirmed infection, whether or not they were wearing a mask, their exposure situation, and other factors. In general, the range of contact is set to 24 hours before the patient with confirmed infection begins to exhibit symptoms. The Korean government is undertaking vigorous measures to track and test those who had been in contact with these patients, by conducting only a proxy interview with the patient.

Objective methods are also used for contact verification, including use of a GPS and review of medical facility records, card transaction logs, and closed-circuit television recordings. Since the government tracks the movements of patients with confirmed COVID-19 in detail and discloses them to the public via a smartphone app, users can determine whether or not they have been in contact with the patient themselves [13]. If these contact individuals do not have any notable symptoms, he or she is released from the mandatory quarantine period a day after a fortnight has passed from the date of final contact with the patient with confirmed diagnosis. In cases where the patient was residing with a family, de-isolation was permissible 14 days after the patient was de-isolated. Individuals violating self-isolation guidelines were imposed with a fine of up to US $1000 or imprisonment for up to 1 year [9].

If the health center recognizes a patient with confirmed COVID-19 first, it reports to the provincial government and KCDC immediately. Thereafter the health center evaluates the severity of the case by checking the patient’s level of consciousness, body temperature, respiration rate, and other high-risk indicators to decide which of the following isolation methods would be most appropriate: (1) self-isolation, (2) facility isolation, or (3) hospital isolation [9]. If the patient has no severe symptoms, no problem with arranging for daily essential supplies, and can live independently, he or she is eligible for self-isolation. However, if the patient has difficulties in living independently, does not have a proper residence, or lives with relatives belonging to a high-risk group (ie, people aged over 65 years, having underlying diseases, or requiring oxygen treatment due to reduced oxygen saturation <90% in indoor settings), he or she should be admitted to a life care center. If the physician in charge determines that the patient’s disease severity is acceptable for his or her transfer to a life care center, a hospitalized patient can be moved into facility isolation. Patients belonging to the high-risk group or having high fever (>38.5℃) require hospital isolation [9].

South Korea has a National Health Insurance System (NHIS) that covers more than 50 million people, that is, over 97.1% of the entire nation’s population, whereas the remaining 2.9% are supported by the Medical Aid Program [14]. The NHIS covers most cases of diagnosis and treatment related to COVID-19, and these insured patients can easily access health facilities with considerably lower medical expenses than those incurred by insured patients in other countries. Patients with COVID-19 are supported by the NHIS, central government, and local governments. Of the total medical expenses, the government and local governments support the expenses incurred by the patients, after subtracting NHIS’ levy of the total medical expenses, as determined by Korea’s health insurance system.

At first, there were no approved antiviral drugs for COVID-19 treatment in Korea, but later, the government approved some antiviral agents such as remdesivir, an anti-Ebola drug, that were likely used for COVID-19 treatment in other countries,. Patients with confirmed COVID-19 are treated with symptomatic therapy comprising fluid replacement, antipyretics, oxygen therapy, or antibiotics to prevent secondary infections. Individuals who have been in contact with these patients do not require any special treatment until they show COVID-19–related symptoms [15].

To reinforce infection control within health care institutions, the Korean government has been providing infection control guidelines to these institutions and focusing on expanding cooperation and communication within the health care circles. Health care institutions are required to provide patients with guidance on hygiene, restrict the entry of visitors and control visiting conditions, screen each visitor’s body temperature, and mandate the wearing of masks [16].

The Korean government designated 60 institutions for hospitalized treatment of patients with COVID-19, managed the supply empirical therapies, and shared distributor information. Moreover, the Korean government is trying to ensure non–COVID-19 patients’ safety and accessibility to hospitals by separating areas for patients with respiratory illnesses from those for patients with other illnesses. As of September 30, 270 hospitals in Korea were designated as COVID-19 protection hospitals, as a result of which many non–COVID-19 patients were not inconvenienced in using medical institutions [10]. The South Korean government also allows physicians to offer over-the-phone medical consultation and prescriptions temporarily, until the COVID-19 outbreak ends. Telemedicine services were previously considered illegal in South Korea, but the government effected a decision to allow telemedicine in order to lower the risk of COVID-19 infection by reducing contact between patients and health care workers.

According to a previous study [1] on the Infectious Disease Prevention and Management Act, the Minister of Health and Welfare or the head of a local government may restrict the assembly, in order to prevent the spread of infectious diseases and may impose a fine up to ₩ 3 million (US $2382.27 as of March 18, 2020) to those in violation of the prohibited measures. During the COVID-19 outbreak, the local governments identified some groups that held large-scale rallies and penalized them. In addition, the Ministry of Health and Welfare reorganized the entire quarantine system to effectively respond to the COVID-19 outbreak and supplemented the necessary measures to respond to an infectious disease outbreak. Thus, 3 amendments to the Act on the Prevention and Management of Infectious Diseases, the Quarantine Law, and the Medical Law were urgently proposed, and these became effective after they were passed in the plenary session of the National Assembly on February 26, 2020 [17]. The current tools and policies are based on the “Infectious Disease Control and Prevention Act,” the legal framework for the Korea’s disease-prevention policy which was revised in 2015 after the outbreak of Middle East respiratory syndrome. South Korea’s experience with this infectious disease enabled rapid amendments of associated laws. The detailed points of the amendments to the law are presented in Table S2 and supplementary text in Multimedia Appendix 1.

COVID-19 is known to be spread through droplets generated by cough or sneezing and by touching one’s eyes, nose, or mouth with contaminated hands. In addition, aerosols and feces are known to be associated with the spread of the disease [18-20]. Considering these facts, the Korean government has suggested various methods for preventing the spread of COVID-19; these include personal hygiene management, the use of masks, and practicing social distancing. In particular, due to the shortage of masks for the public, the government made a policy to enable people to purchase 2 masks per week per person from March 9, 2020. The detailed policies undertaken by the government to enhancing personal hygiene measures are presented in the Table S2 and supplementary text in Multimedia Appendix 1.

However, even if the public adheres to all the above-mentioned preventive measures, doctors who consult outpatients are still at high-risk of exposure. In order to reduce their risk, the government has installed temperature-screening devices at the entrances of hospitals and asked all visitors to complete a self-questionnaire to be able to record their contact history and travelling history, as well as fever and respiratory symptoms. In addition, outpatient doctors are required to wear personal protective equipment, including a mask, and to maintain a distance of at least 2 meters from the patient [16]. For instance, Severance Children’s Hospital in Seoul was able to successfully adopt this policy to contain the spread of infection from the outpatient to inpatient departments (see supplementary text in Multimedia Appendix 1).