| Objective To analyze and compare the clinical and chest CT imaging features of patients infected with SARS-Co V-2 Delta variant and Omicron variant in high-altitude areas(>1000m)of Gansu province,and to explore the clinical and CT imaging characteristics of patients infected with in high-altitude areas,so as to provide scientific basis for the prevention and treatment of SARS-Co V-2 in high-altitude areas.Methods A retrospective study was conducted to collect 1439 confirmed cases admitted to Lanzhou Heavy Ion Hospital from October 1,2021 to September 31,2022.After screening according to the inclusion and exclusion criteria,a total of 418 cases were included as the research objects.A total of 103 cases infected with Delta variant(Delta group)and 315 cases infected with Omicron variant(Omicron group)were included.The demographic data,clinical features,laboratory tests,antibody levels,chest CT imaging features and clinical prognosis of the two groups were compared and analyzed.Results A total of 418 confirmed cases were enrolled,including 103 cases in Delta group and 315 cases in Omicron group.There were 180 males(43.1%)and 238females(56.9%).The median age of the two groups was 42 years and 36 years,respectively.There were mainly mild patients in the two groups.The proportion of ordinary and heavy patients was significantly higher in the Delta group than in the Omicron group;the difference was statistically significant when comparing the clinical typing of the two groups(χ2=43.782,P < 0.05).The full vaccination rate of the new coronavirus vaccine was 32.3%(135/418),with a higher rate of full vaccination in the Omicron group than in the Delta group,The difference between the groups was statistically significant(χ2= 52.202,P < 0.001);A higher proportion of patients in the Omicron group than in the Delta group had been diagnosed and had received their last vaccination for more than 6 months,with a statistically significant difference(χ2= 39.587,P < 0.001);A total of 112 blood type samples were collected,of which 35 cases(31.3%)were blood type A and 39 cases(34.8%)were blood type B,which accounted for more than 13 cases(11.6%)of AB and 25 cases(22.3%)of O,and there was no significant difference between the groups(both P >0.05).The negative conversion time of nucleic acid in patients living at an altitude of ≥1500meters was longer than that in patients living at an altitude of 1000-1500 meters,and the difference was statistically significant(Z=-2.912,P=0.04).The median time of nucleic acid negative conversion(the duration of nucleic acid positive before and after admission)in Delta group and Omicron group was 18 days and 12 days,and the median length of hospital stay was 15 days and 10 days,respectively,and the differences were statistically significant(Z=-9.379,-9.971,all P<0.05).The most common clinical symptoms of patients are cough and phlegm,followed by fever,sore throat,muscle and joint pain,etc.The proportion of patients with fever was higher in the Omicron group than in the Delta group [48.3%(152/315)vs.16.5%(17/103)],with a statistically significant difference(χ2=34.482,P<0.05).Ninety-six patients(23.0%)in both groups had one or more comorbidities,and patients in the Delta group had more comorbidities.The results of laboratory tests showed that 49 patients(11.7%)had lymphocytopenia,including 5 patients(4.9%)in Delta group and 44patients(14.0%)in Omicron group,and the differences were statistically significant(χ2=6.230,P=0.013).The proportion of patients with elevated procalcitonin and serum amyloid A levels in the Delta group was lower than that in the Omicron group,and the difference was statistically significant(χ2=40.517,29.498,P<0.05).258 patients(70.1%)had elevated Ig G antibody level at admission,and the proportion of patients in the Delta group was higher than that in the Omicron group,with a statistically significant difference(χ2=7.319,P=0.007).The increase rate of Ig M antibody level in Delta group was higher than that in Omicron group,and the difference was statistically significant(χ2=49.425,P<0.001).Analysis of the chest CT data showed that there were statistically significant differences in the total volume of whole lung lesions/whole lung volume and volume of whole lung ground glass lesions/whole lung volume between the two groups(P<0.05).Conclusions Patients infected with Delta and Omicron variant were mainly mild.The proportion of common and severe cases in patients infected with Delta variant was higher than that in patients infected with Omicron variant.Patients infected with Omicron variant had more common fever and upper respiratory symptoms,fewer inflammatory lesions on lung CT,shorter viral nucleic acid clearance time and hospital stay.The higher number of infections with Omicron variant,most diagnosed more than 6 months after the last vaccination,is related to local vaccination policies and lower protective antibody titers after vaccination.Altitude can affect the viral nucleic acid clearance time and hospitalization time of SARS-Co V-2 infected patients. |
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