Clinical value analysis of IgM and IgG antibodies detected by nucleic acid in patients with COVID-19.

Ding, Tao; Zhang, Nengping

OBJECTIVE We aimed to analyze the clinical diagnostic value of nucleic acid detection and specific IgM and IgG antibodies in COVID-19 patients. According to the patients' test outcomes of nucleic acid and specific IgM and IgG antibodies, the patients were grouped. METHODS Medical records of 788 COVID-19 patients were collected for retrospective analysis, including demographic data, clinical characteristics, CT outcome and laboratory indicators. According to the patients' nucleic acid detection and the results of specific IgM and IgG antibodies, the patients were grouped, and the clinical application value of COVID-19 nucleic acid detection and specific IgM and IgG antibodies was analyzed. RESULTS The main clinical manifestations of COVID-19 patients included in this study were fever (431 cases, 54.7%), cough (404 cases, 51.3%), and fatigue (232 cases, 29.4%), and the main comorbidities were hypertension (201 Cases, 25.4%), diabetes (86 cases, 10.9%), coronary heart disease (39 cases, 4.9%), etc. CT abnormalities mainly manifested as ground glass shadows (731 cases, 92.8%), mesh nodules shadows (413 cases, 52.4%), pulmonary fibrosis (118 cases, 15.0%), etc. The majority of patients were positive for IgM and IgG antibodies. There were 50 patients in the qPCR+IgM-IgG- group (only nucleic acid test result was positive), of which 6 patients (12%) were mild in symptoms, and 39 patients (78%) had mild CT findings. There were 321 patients in the qPCR+IgM+IgG+ group (nucleic acid and specific IgM and IgG antibody test results were positive), of which 49 patients (15.5%) were severe or critically ill, and 78 patients (24.8%) had severe CT findings. There were 291 patients in the qPCR-IgM+IgG+ group (specific IgM and IgG antibody test results were positive), of which 22 (7.5%) were severe or critically ill, and 94 (32.3%) patients had severe CT findings. The sensitivity of antibody detection for COVID-19 was higher than that of qPCR (84.9%, 86.4% vs. 53.9%, P<0.001). There were significant differences between IgM+ patients and IgM- patients in terms of age distribution, gender, sore throat, clinical classification, and CT findings (P<0.05). CONCLUSION IgM antibody has a high clinical detection rate, which effectively avoids the missed detection of qPCR and increases the detection rate of COVID-19 patients. There are more severe and critically ill patients with IgM tested positive, which finding has certain guiding significance for clinical diagnosis and treatment.