Sources of Infection Among Confirmed Cases of COVID-19 in Jeju Province, Korea

Abstract

This study analyzed the sources of infection among confirmed cases in Jeju Province, a self-governed island. Methods:The sources of infection were broadly categorized as follows: (1) infections from overseas (confirmed patients who reported travel overseas or contact with overseas travelers); (2) infections from outside Jeju Province (confirmed patients who had visited other provinces or had contact with individuals who had traveled to other provinces in Korea); and (3) unknown sources of infection (confirmed patients who were infected following contact with an infected person whose source of infection was unknown). The chi-square test was used to analyze the differences in the distributions of related variables for each source of infection.Results: Of the 627 confirmed cases, 38 (6.1%) were infections from overseas sources, 199 (31.7%) were from outside of Jeju Province, and 390 (62.2%) were from unknown sources. Jeju Province had no cases with an unknown source of infection during the first and second waves of the nationwide outbreak. Conclusions:Infections from overseas sources could be blocked from spreading to local communities in Jeju Province by conducting screening at the airport, along with the preemptive suspension of visa-free entry. In addition, considering the scale of the nationwide outbreak, measures must be established to delay outbreaks from unknown sources of infection caused by sources outside Jeju Province.

Clinical Characteristics and Risk Factors for Severe Disease of Coronavirus Disease 2019 in a Low Case Fatality Rate Region in Korea

“…Of all the patients who were diagnosed with COVID-19 in Jeju island in 2020, 6.1% were from overseas and 31.7% were from areas in Korea other than the Jeju Province. In addition, there was an increase in the incidence rate due to unknown sources from the third wave of the nationwide outbreak [ 11 ]. In this study, the proportion of native residents of Jeju island and patients exposed to SARS-CoV-2 within Jeju island was 77.1% and 75.9%, respectively.…”

“…Influx case from outside Jeju Island (mainland) was defined as those patients who had visited other cities in Korea or had contact with confirmed cases in other cities. Patients who had unidentifiable source of infection or had contact with confirmed cases which occurred in large-scale clusters were categorized to have an unknown source of infection [ 4 11 ].…”