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. 2021 Apr 12;43(1):35-41.
doi: 10.1093/pubmed/fdaa158.

Risk of severe coronavirus disease in imported and secondary cases in Zhejiang province, China

Fan He  1 , Xiaopeng Shang  1 , Tiehong Fu  2 , Junfen Lin  1 , Fudong Li  1 , Yinwei Qiu  1 , Chen Wu  1 , Zhen Wang  1
Affiliations

Risk of severe coronavirus disease in imported and secondary cases in Zhejiang province, China

Fan He et al. J Public Health (Oxf). .

Abstract

Background: To our knowledge, no previous studies have focused on determining whether the virulence and case fatality rate of the severe acute respiratory coronavirus 2 (SARS-CoV-2) decreases as the virus continues to spread. Hence, our aim was to retrospectively explore the differences in the risk of severe or critical COVID-19 among imported, secondary and tertiary cases in Zhejiang, China.

Methods: We categorized COVID-19 cases reported by hospitals in Zhejiang as first-, second- and third-generation cases. Univariate and multivariate logistic regression analyses were performed to compare disease severity and case generation.

Results: Of 1187 COVID-19 cases, 227 (19.1%, 95% CI: 16.9-21.4) manifested severe or critical illness. The adjusted risk difference for severe or critical illness was lower for second- (odds ratio (OR) = 0.84, 95% confidence interval (CI): 0.52-1.36) and third-generation (OR = 0.55, 95% CI: 0.37-0.83) cases than for first-generation cases. Compared with hospitalized patients, cases identified at centralized isolation locations (OR = 0.62, 95% CI: 0.40-0.97) and those identified through active search or gateway screening (OR = 0.28, 95% CI: 0.08-1.04) were at a lower risk of severe or critical illness.

Conclusions: Second- and third-generation cases of COVID-19 have a lower risk of developing severe or critical illness than first-generation cases.

Keywords: COVID-19; community-acquired infections; coronavirus disease; odds ratio; risk assessment.

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Figures

Fig. 1
Fig. 1
Epidemic curve for COVID-19 cases (1-day intervals) in Zhejiang province, China, from 5 January to 19 February 2020, (n = 1187).
See this image and copyright information in PMC

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