Clinical Features of Adult COVID-19 Patients without Risk Factors before and after the Nationwide SARS-CoV-2 B.1.617.2 (Delta)-variant Outbreak in Korea: Experience from Gyeongsangnam-do

• Published in: Journal of Korean medical science 2021, 36(49), , pp.1-9
• Main Authors: Ryu, Byung-Han, Hong, Sun In, Lim, Su Jin, Cho, Younghwa, Hwang, Cheolgu, Kang, Hyungseok, Kim, Si-Ho, Wi, Yu Mi, Hong, Kyung-Wook, Bae, In-Gyu, Cho, Oh-Hyun
• Format: Article
• Language: English
• Subjects: Adult; COVID-19 - diagnosis; COVID-19 - epidemiology; Disease Outbreaks; Female; Hospitalization; Humans; Incidence; Male; Middle Aged; Odds Ratio; Original; Republic of Korea - epidemiology; Retrospective Studies; Risk Factors; SARS-CoV-2; Time Factors; 의학일반
• ISSN: 1011-8934; 1598-6357
• DOI: 10.3346/jkms.2021.36.e341

Data on severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) delta variant virulence are insufficient. We retrospectively compared the clinical features of adult coronavirus disease 2019 (COVID-19) patients without risk factors for severe COVID-19 who entered residential treatment centers (RTCs) before and after the delta variant outbreak. We collected medical information from two RTCs in South Korea. On the basis of nationwide delta variant surveillance, we divided the patients into two groups: 1) the delta-minor group (diagnosed from December 2020-June 2021, detection rate < 10%) and 2) the delta-dominant group (diagnosed during August 2021, detection rate > 90%). After propensity-score matching, the incidences of pneumonia, hospital transfer and need for supplemental oxygen were compared between the groups. In addition, risk factors for hospital transfer were analysed. A total of 1,915 patients were included. The incidence of pneumonia (14.6% vs. 9.2%, = 0.009), all-cause hospital transfer (10.4% vs. 6.3%, = 0.020) and COVID-19-related hospital transfer (7.5% vs. 4.8%, = 0.081) were higher in the delta-dominant group than those in the delta-minor group. In the multivariate analysis, the delta-dominant group was an independent risk factor for all-cause (adjusted odds ratio [aOR], 1.91; 95% confidence interval [CI], 1.16-3.13; = 0.011) and COVID-19-related hospital transfer (aOR, 1.86; 95% CI, 1.04-3.32; = 0.036). Hospitalization rates were increased in the adult COVID-19 patients during the delta variant nationwide outbreak. Our results showed that the delta variant may be more virulent than previous lineages.