Epidemiological characteristics analysis of re-positive patients infected with COVID-19 Delta variant strains
Objective To analyze the epidemiological characteristics of the re-positive patients in two COVID-19 outbreaks caused by Delta variant strains in Ningbo,to provide a scientific basis for bet-ter management.Methods The epidemiological and clinical information of the re-positive patients in two COVID-19 outbreaks in Ningbo from December 6,2021,to May 31,2022,were collected.The epidemi-ological characteristics,clinical manifestations,infectivity,and influencing factors were analyzed.Re-sults A total of 112 patients with COVID-19 infection were included in this study,of which 65 were re-positive,the re-positive rate was 58.04％.Gender,age,occupation,vaccination,clinical severity,and genotype of delta strain did not affect the re-positive of previously infected patients(all P＞0.05).The median hospital stay of re-positive was 5.00(3.25,8.75)days,which was shorter than the median stay of 25.00(22.00,31.50)days after the first diagnosis(U=-6.724,P＜0.001).All the re-positive per-sons were asymptomatic,and their clinical severity was lighter than that after the first diagnosis(x2=1.888,P＜0.001).The infection rate of close contacts of the re-positive persons was lower than the infec-tion rate after the case was first diagnosis(0.00％:1.67％,P=0.262),but the difference was not sta-tistically significant.Conclusions Re-positive persons with previous infections of the COVID-19 Delta variant had no clinical symptoms and no infectivity.It is recommended that nucleic acid testing and isola-tion should not be carried out within the second half of the year after excluding secondary infection.
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