Epidemiological characterization of a cluster of COVID-19 caused by SARS-CoV-2 Omicron variant at a construction site in Qingpu Districtï¼ Shanghai
Journal Title: Shanghai Journal of Preventive Medicine - Year 2023, Vol 35, Issue 1
Abstract
ObjectiveTo determine the epidemiological characteristics of a cluster of SARS-CoV-2 Omicron variant at a construction site and provide evidence for further COVID-19 prevention and control.MethodsDemographic data of all COVID-19 cases at a construction site in Qingpu Districtï¼ Shanghaiï¼ and basic information of the construction site were retrospectively collected through filed investigation. Descriptive epidemiology was used for the analysis. Basic reproduction number ï¼R0ï¼ and time-dependent reproduction number ï¼Rtï¼ were calculated using R program.ResultsDuring April 12 and May 8ï¼ 2022ï¼ a total of 314 cases were reported at the construction siteï¼ with an attack rate of 60.62%. The attack rate significantly differed between workers and managers ï¼Ï2=10.868ï¼ P<0.001ï¼ï¼ whereas did not differ statistically by gender ï¼Ï2=0.358ï¼ P=0.550ï¼ or by vaccination status ï¼Ï2=2.861ï¼ P=0.091ï¼. The age of all cases ranged from 5 months of age to 68 yearsï¼ with a media age of 49.0 years ï¼interquartile rangeï¼ 39.8ï¼ 54.0ï¼. In all casesï¼ male was predominant ï¼83.44%ï¼. Moreoverï¼ the epidemic was mainly concentrated in the workersâ dormitory areaï¼ with infected cases identified in all buildings of each dormitory area. The attack rate ranged between 33.33% and 87.50% across the buildings. Symptoms and signs were observed among 43.0% of all casesï¼ of which major clinical manifestations included cough ï¼33.33%ï¼ï¼ fever ï¼30.37%ï¼ and headache ï¼17.04%ï¼. Clinical manifestations did not differ by gender ï¼Ï2=1.275ï¼ P=0.259ï¼ or by vaccination status ï¼Ï2=0.186ï¼ P=0.666ï¼. Additionallyï¼ R0 was estimated to be 6.08 ï¼95% confidence intervalï¼ 4.49â8.02ï¼. The Rt showed a decline in the beginningï¼ followed by an increase and a re-decline.ConclusionThe cluster epidemic of COVID-19 caused by Omicron variant at the construction site is highly contagiousï¼ spreads rapidly and quietlyï¼ causes mild symptomsï¼ which finally resulted in a large number of infected cases. It warrants rapid and strict containment when an epidemic occurs at construction sites.
Authors and Affiliations
CHEN Jianfeng,FANG Liping,LI Yongqi,
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