J Korean Med Sci.  2021 Dec;36(49):e341. 10.3346/jkms.2021.36.e341.

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

• Ryu BH
• Hong SI
• Lim SJ
• Cho Y
• Hwang C
• Kang H
• Kim SH
• Wi YM
• Hong KW
• Bae IG
• Cho OH

• KMID: 2523556
• DOI: http://doi.org/10.3346/jkms.2021.36.e341

Abstract

Background
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.
Methods
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.
Results
A total of 1,915 patients were included. The incidence of pneumonia (14.6% vs. 9.2%, P = 0.009), all-cause hospital transfer (10.4% vs. 6.3%, P = 0.020) and COVID-19-related hospital transfer (7.5% vs. 4.8%, P = 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; P = 0.011) and COVID-19-related hospital transfer (aOR, 1.86; 95% CI, 1.04–3.32; P = 0.036).
Conclusion
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.

Keyword

COVID-19; Delta Variant; Virulence; Hospitalization; South Korea

Figure

• 

  Fig. 1 Kaplan-Meier curves for all-cause (A) and COVID-19-related hospital transfer (B) in the propensity-score-matched cohort.COVID-19 = coronavirus disease 2019.

Reference

1. World Health Organization. Weekly epidemiological update on COVID-19 - 31 August 2021 (edition 55). Updated 2021. Accessed September 7, 2021. https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19---31-august-2021 .

2. Korea Disease Control and Prevention Agency. Global trends and characteristics of the SARS-CoV-2 Delta variant. Public Health Wkly Rep. 2021; 14(33):2363–2365.

3. Korea Disease Control and Prevention Agency. July 2021 status and characteristics of the COVID-19 variant virus outbreak in the Republic of Korea. Public Health Wkly Rep. 2021; 14(48):3388–3396.

4. Public Health England. SARS-CoV-2 variants of concern and variants under investigation in England: technical briefing 14. Updated 2021. Accessed September 7, 2021. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/991343/Variants_of_Concern_VOC_Technical_Briefing_14.pdf .

5. Sheikh A, McMenamin J, Taylor B, Robertson C. Public Health Scotland and the EAVE II Collaborators. SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet. 2021; 397(10293):2461–2462. PMID: 34139198.

6. Herlihy R, Bamberg W, Burakoff A, Alden N, Severson R, Bush E, et al. Rapid increase in circulation of the SARS-CoV-2 B.1.617.2 (Delta) variant - Mesa County, Colorado, April-June 2021. MMWR Morb Mortal Wkly Rep. 2021; 70(32):1084–1087. PMID: 34383734.

7. Fisman DN, Tuite AR. Progressive increase in virulence of novel SARS-CoV-2 variants in Ontario, Canada. medRxiv. Forthcoming. 2021; DOI: 10.1101/2021.07.05.21260050.

8. Ong SWX, Chiew CJ, Ang LW, Mak TM, Cui L, Toh M, et al. Clinical and virological features of SARS-CoV-2 variants of concern: a retrospective cohort study comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta). Clin Infect Dis. 2021; ciab721. PMID: 34423834.

9. Korea Disease Control and Prevention Agency. Analysis rate and detection rate of COVID-19 mutant virus in Korea. Updated 2021. Accessed September 15, 2021. https://www.kdca.go.kr/contents.es?mid=a20107040000 .

10. Twohig KA, Nyberg T, Zaidi A, Thelwall S, Sinnathamby MA, Aliabadi S, et al. Hospital admission and emergency care attendance risk for SARS-CoV-2 delta (B.1.617.2) compared with alpha (B.1.1.7) variants of concern: a cohort study. Lancet Infect Dis. 2021; S1473-3099(21)00475-8.

11. Luo CH, Morris CP, Sachithanandham J, Amadi A, Gaston D, Li M, et al. Infection with the SARS-CoV-2 Delta variant is associated with higher infectious virus loads compared to the alpha variant in both unvaccinated and vaccinated individuals. medRxiv. Forthcoming. 2021; DOI: 10.1101/2021.08.15.21262077.

12. Fajnzylber J, Regan J, Coxen K, Corry H, Wong C, Rosenthal A, et al. SARS-CoV-2 viral load is associated with increased disease severity and mortality. Nat Commun. 2020; 11(1):5493. PMID: 33127906.

13. Zhang J, Xiao T, Cai Y, Lavine CL, Peng H, Zhu H, et al. Membrane fusion and immune evasion by the spike protein of SARS-CoV-2 Delta variant. Science. 2021; eabl9463.

14. Singh J, Rahman SA, Ehtesham NZ, Hira S, Hasnain SE. SARS-CoV-2 variants of concern are emerging in India. Nat Med. 2021; 27(7):1131–1133. PMID: 34045737.