Severity of COVID-19 Associated with SARS-CoV-2 Variants Circulating in the Republic of Korea

Abstract

We aimed to identify the severity of the Coronavirus disease 2019 specifically according to the SARS-CoV-2 variant in the Republic of Korea by describing the number of severe/critical cases and deaths, case severity rate (CSR) and case fatality rate (CFR). A total of 23,496,849 confirmed cases were reported during January 20, 2020 to September 3, 2022. 26,472 (0.11%) cases were considered severe/critical and 27,471 (0.12%) resulted in death. The omicron BA.1/BA.2 period showed most severe/critical cases and deaths accounting for 40.7% (10,772 patients) and 66.4% (18,252 patients), respectively. In the omicron variant dominant period, the proportion of the age 80 and over saw on increase in severe/critical cases and deaths by 26.4%p, 7.4%p, respectively, than those in the delta dominant period. The CSR and CFR were 0.20% and 0.12% over that period. The CSR decreased from 2.98% in the pre-delta dominant period to 2.14% in the delta dominant period, and 0.14% in the omicron BA.1/BA.2 period. CFR was also highest at 1.15% in the pre-delta dominant period and decreased to 0.95% in the delta dominant period, 0.10% in the omicron BA.1/BA.2 period. Despite the increase in severity of the delta variant, overall severity decreased in the delta dominant period showing continuous decrease in the omicron dominant period. In the omicron dominant period, the proportion of the elderly of severe/critical and fatal condition increased which suggests the importance of focusing on the response strategy of the elderly.

Comparative Analysis of Clinical Outcomes Using Propensity Score Matching: Coronavirus Disease 2019 vs. Seasonal Influenza in Korea

“… 22 28 In our study, the pre-omicron group included patients with both alpha and delta variants. 20 Differences in study populations between our study and these previous ones may explain this discrepancy. Dyspnea is a subjective symptom, and most previous studies have not used an objective scale to evaluate it.…”

“…The omicron variant became prevalent in 2022 following its first case reported from South Korea on November 25, 2021. 19 20 Data for influenza patients were extracted from 2018–2019. Ideally, patients from the same year would be compared, but during the COVID-19 pandemic (2021–2022), only 71 adult patients with influenza were registered in the SARI system.…”

Characteristics of Critically Ill COVID-19 Patients in Busan, Republic of Korea

“…During the period of delta variant prevalence, men accounted for 57.6% of cases in the nation and 54.8% in Busan. In terms of the distribution of unvaccinated people, during the period when the delta strain was not prevalent, the proportion of people who had not been vaccinated was 97.3% nationwide and 98.3% in Busan, and during the period when the delta variant was prevalent, the proportion of people who had not been vaccinated was 60.6% nationwide and 57.7% in Busan [ 22 ].…”

“…A reserve bag can be attached to treat emergency cases that require a very high concentration of oxygen (≥10 L/min). In the third step, devices that continuously supply of oxygen, such as a high-flow nasal cannula or optiflow can be used for a high flow rate of 60 L/min irrespective of the patient’s breathing pattern [ 22 ]. High-flow oxygen therapy, mechanical ventilation, and ECMO can be used for critically ill patients who meet the following criterion for admission to the ICU: “A person who needs or is expected to need more than the supply of invasive mechanical ventilation.” In addition to those receiving ECMO and CRRT, those receiving oxygen over 5 L/min are included [ 3 , 23 ].…”

Analysis of pregnant women with critically severe COVID-19 in Republic of Korea from February 2020 and December 2021

“…In Korea, the rate of critically severe cases among all ages was 2.98% before the predominance of the Delta variant and 2.14% during the Delta-predominant period. During the same period, the rate of critically severe COVID-19 cases among patients aged 20 to 40 years was less than 1%, whereas pregnant women had a higher rate of critically severe COVID-19 cases [ 16 ]. However, the total fatality rate for all age groups was 0.89% (5,625/635,253 people) [ 17 , 18 ], while that for pregnant women was 0.04% (1/2,233 people), which was 22.3 times lower than the total fatality rate.…”