快速抗原检测在新型冠状病毒感染中的应用评价

Diagnostic value of rapid antigen testing for the detection of SARS-CoV-2 infection

目的评价快速免疫层析法抗原检测在新型冠状病毒症状性感染患者中的诊断价值。方法前瞻性研究,研究对象为2022年5月20日至6月5日复旦大学附属儿科医院(上海市新型冠状病毒感染患儿定点医院)新型冠状病毒肺炎隔离病房确诊住院的76例新型冠状病毒症状性感染的患儿和其确认感染的55例陪护家属。连续采集其鼻咽拭子标本,采用实时荧光定量反转录PCR方法检测新型冠状病毒核酸,同时用免疫层析法检测新型冠状病毒抗原。评价抗原检测结果与核酸循环阈(Ct)值变化的相关性及新型冠状病毒抗原检测在患者发病后不同时期的灵敏度与特异度,采用Kappa检验分析2种检测方法的一致性。结果新型冠状病毒症状性感染患者中,患儿76例(男41例、女35例),患病年龄5(2,9)岁;陪护家属55例(男8例,女47例),患病年龄38(32,41)岁。对采集的所有478份鼻咽拭子样本同时进行了新型冠状病毒抗原与核酸扩增检测。自发病至新型冠状病毒核酸检测转阴性的任何时期,快速抗原检测的总体灵敏度和特异度分别为48.2%(119/247)和98.3%(227/231),抗原检测与核酸检测显示中等度的一致性(κ=0.46,P<0.05)。Ct值≤25,抗原检测灵敏度均为100.0%(82/82);Ct值为26,灵敏度为8/10;Ct值为30,灵敏度为4/15;Ct值为35,灵敏度为8.3%(3/36);Ct值>35,抗原检测均为阴性。发病1~2、3~5、6~7、8~10、>10 d抗原检测的灵敏度分别为5/8、90.2%(37/41)、88.9%(24/27)、45.0%(36/80)、18.7%(17/91),特异度分别为5/5、5/5、2/2、94.1%(32/34)、98.9%(183/185)。病程2~7 d,患者鼻咽拭子的Ct值均<26;病程第8天时,Ct值为28.7±5.0,病程第13天时,Ct值为34.5±2.9,病程第14天后,Ct值均>35。结论快速免疫层析法抗原检测新型冠状病毒在发病后7 d内具有较高的灵敏度和特异度,其灵敏度与患者的病毒载量呈正相关和发病时间呈负相关。

Objective To investigate the diagnostic value of rapid antigen test based on colloidal gold immunochromatographic assay for the detection of SARS-CoV-2 infection in symptomatic patients.Methods From May 20 to June 52022,76 hospitalized children and their 55 accompanying family members with confirmed SARS-CoV-2 infection in the COVID-19 isolation unit of the Children′s Hospital of Fudan University(designated referral hospital for SARS-CoV-2 infection in Shanghai)enrolled.Their nasopharyngeal swab specimens were consecutively collected.The samples were tested for SARS-CoV-2 nucleic acid by real-time quantitative.SARS-CoV-2 antigen was tested by immunochromatography.The correlation between the antigen detection results and the change of the cycle threshold(Ct)values were evaluated,as well as the sensitivity and specificity of SARS-CoV-2 antigen detection at different periods after the onset of the disease.Kappa consistency test was conducted to investigate the consistency between the 2 diagnostic methods.Results Of the enrolled SARS-CoV-2 symptomatic infections,76 were children,including 41 males and 35 females,with an age of 5(2,9)years;55 were accompanying families,including 8 males and 47 females,with an age of 38(32,41)years.All 478 samples were simultaneously tested for SARS-CoV-2 antigen and nucleic acid.In any period from disease onset to negative conversion of viral nucleic acid,the overall sensitivity of the rapid antigen test was 48.2%(119/247),the specificity was 98.3%(227/231),and antigen test and nucleic acid test showed moderate consistency(κ=0.46,P<0.05).The sensitivity of antigen test was 100%(82/82)when the Ct value was≤25.And the sensitivity of antigen test was 8/10,4/15 and 8.3%(3/36)when the Ct value was 26,30 and 35,respectively.All antigen tests were negative when Ct value was>35.During the period of 1-2 days,3-5 days,6-7 days,8-10 days and>10 days after onset,the sensitivity and specificity of SARS-CoV-2 antigen test were 5/8 and 5/5,90.2%(37/41)and 5/5,88.9%(24/27)and 2/5,45.0%(36/80)and 94.1%(32/34),18.7%(17/91)and 98.9%(183/185)respectively.The Ct values of nasopharyngeal swabs were<26 during 2 to 7 days after onset,28.7±5.0 on day 8,34.5±2.9 on day 13 and>35 after 14 days,respectively.Conclusion SARS-CoV-2 antigen test in the patients with SARS-CoV-2 infection shows acceptable sensitivity and specificity within 7 days after onset of disease,and the sensitivity was positively correlated with viral load and negatively correlated with onset time.