key: cord-350715-x92g6bnk authors: Zheng, Yutong; Yan, Meitian; Wang, Lan; Luan, Liang; Liu, Jing; Tian, Xiao; Wan, Nan title: Analysis of the application value of serum antibody detection for staging of COVID‐19 infection date: 2020-07-23 journal: J Med Virol DOI: 10.1002/jmv.26330 sha: doc_id: 350715 cord_uid: x92g6bnk Coronavirus disease 2019 (COVID‐19) has now spread all over the world. The National Health Commission of the People's Republic of China reported 78,439 cured and discharged cases, 4634 deaths, 83,462 confirmed cases and 760,818 close contacts as of June 25, 2020. Joint detection of nucleic acids and antibodies has become an important laboratory diagnostic for COVID‐19 patients. Disease progression and infection stage can be established based on the biological characteristics of these tests. However, there have been few studies of the different infection stages of COVID‐19. We conducted a retrospective analysis to explore the clinical characteristics of COVID‐19 patients at different infection stages and to characterize the characteristics of specific serum antibodies at each stage. These data will provide a theoretical basis for clinical diagnosis and treatment. This article is protected by copyright. All rights reserved. patients. In this study we explored the clinical value of specific serum antibody detection in COVID-19 patients. Nucleic acid and specific antibody detection SARS-CoV-2 nucleic acids in nasopharyngeal swab samples were detected using a model 7500 PCR gene amplification instrument (ABI, Foster City, CA, USA). A cycle threshold value of > 40 was considered negative and a value of <40 was considered positive. Fasting venous blood (2-5 mL) was collected and centrifuged. The serum was separated and stored at -20°C. Specific serum IgM and IgG antibodies were quantitatively detected using an Axceed 260 magnetic particle-based chemiluminescence immunoanalyzer (Bioscience, Tianjin, China). A chemiluminescence signal cutoff value (S/co) of <1 was considered negative and >1 was considered positive. This article is protected by copyright. All rights reserved. Statistical methods SPSS Statistics software version 25.0 (IBM, Armonk, NY, USA) was used for all statistical analyses. Count data were expressed as frequency (%) and the chi-square test was used to assess differences between groups. Continuous data with normal distributions were expressed as x ±s, and differences between two groups or among multiple groups were assessed using the student's T test and analysis of variance, respectively. Non-normally distributed variables were expressed as medians and interquartile ranges and differences between groups were assessed using the Mann-Whitney U test. Graphpad Prism 7.0( Graphpad Software,San Diego,CA)was used to produce all figures. A total of 723 COVID-19 patients were enrolled, comprising 290 male patients and 433 female patients with an average age of 61.30±14.55 years. Moderate cases made up the largest number of patients, accounting for 72.20% of the total. Mild cases were rarest, accounting for only 1.11% of the total, while severe and critical cases accounted for 23.24% and 3.46% of the total, respectively. According to the biological characteristics of nucleic acids and specific serum IgM and IgG antibodies, the 723 COVID-19 cases were classified into infection stages ( Table 1) . Analyses of the characteristics of different periods were performed ( Table 2 ). Patients who were nucleic acid negative at admission could be divided into two categories:① the nucleic This article is protected by copyright. All rights reserved. acid test had a positive record, but was negative more than twice before admission, and remained negative many times after admission; or ② nucleic acid test results were negative since the onset of the disease, with diagnosis made based on lung imaging, symptoms, epidemiological history and serum antibody results. Because most patients had a long disease course when they were admitted to hospital, there were more cases in the active, middle/late and convalescent stages of infection (P<0.001). Figure 1A ). This article is protected by copyright. All rights reserved. On January 20, 2020, the National Health Commission decided to include COVID-19 pneumonia in statutory infectious disease category B and to take preventive and control measures for category A infectious diseases 5 . On January 30, the WHO called the epidemic "an emergency of international concern". SARS-CoV-2 is a novel enveloped β coronavirus with an RNA genome. In the early stages of the epidemic, nucleic acid detection was taken as direct evidence of infection. However, the accuracy of nucleic acid detection was affected by the quality of detection kits, sample collection methods, operator ability, RNA stability, patient condition and concurrent drug use 6 This article is protected by copyright. All rights reserved. In addition, we found that levels of IgG were persistently high after the active stage of infection, indicating that disease progression coincided with emergence of these antibodies. We found that levels of IgG in patients with different clinical severity were higher than those of IgM. This finding may be related to the high affinity and easy detection of IgG antibodies and the longer course of disease of the patients included in the study following their admission to hospital. However, levels of serum specific IgM Tables Table 1. Combined analysis of nucleic acid and serum antibody testing. ① The nucleic acid test had a positive record, but was negative more than twice before admission, and remained negative many times after admission.② The nucleic acid test result was negative since the onset of the disease. Table 2 . Analysis of COVID-19 infection stages. Combined detection of two detection methods to determine the stage of infection Nucleic acid+ IgM-IgG-①Window period ②IgM begins to appear but is still below the detection limit in the early stage of infection. This article is protected by copyright. All rights reserved. IgM+IgG-The early stage of infection. The middle and late stage of infection (the result of early antibody test of the patient is unknown, the possibility of recurrent infection can not be ruled out). The active stage of infection, but at this time the body has developed a certain immune capacity. IgM-IgG-It may be in the infection recovery stage where the nucleic acid turns negative, the IgM antibody disappears and the IgG antibody begins to appear but is still below the detection limit. IgM-IgG+ Previous infection. The convalescent stage of infection, IgM decreased but still above the detection limit. Nucleic acid-② IgM-IgG-This type of patient was diagnosed by pulmonary CT, symptoms and epidemiological history on admission. (1) the possible "window period" of false negative nucleic acid. (2) the convalescent stage in which the nucleic acid turned negative, the IgM antibody disappeared and the IgG antibody began to appear but was still below the detection limit. IgM+IgG-May be in the acute stage of infection, consider the possibility of false negative nucleic acid. Consider the possible active stage of infection with false negative nucleic acid. ① The nucleic acid test had a positive record, but was negative more than twice before admission, and remained negative many times after admission. ② The nucleic acid test result was negative since the onset of the disease. As of 24:00 on June 25 th, the latest situation of COVID-19 epidemic situation There are 9211083 confirmed cases by novel coronavirus outside China Consensus of 2019-nCoV nucleic acid testing experts On the issuance of novel coronavirus's diagnosis and treatment plan for pneumonia (seventh edition for trial implementation):Health Office Medical Care Administration File〔2020〕184 [S].Beijing:National Health Commission of the people's Republic of National Health Commission of the people's Republic of China.Pneumonia infected by novel coronavirus is included in the management of legal infectious diseases Cause analysis and countermeasures of false negative results of novel This article is protected by copyright. All rights reserved. Accepted Article coronavirus nucleic acid test False positive analysis of chemiluminescence microparticle immunoassay in HIV detection Ping'an Zhang.The diagnostic value of joint detection of serum IgM and IgG antibodies to 2019-nCoV in 2019-nCoV infection Research progress on mechanism of antibodydependent enhancement Is COVID-19 receiving ADE from other coronaviruses? Immunoregulation with mTOR inhibitors to prevent COVID-19 severity: A novel intervention strategy beyond vaccines and specific antiviral medicines Dengue Fever, COVID-19 (SARS-CoV-2), and Antibody-Dependent Enhancement (ADE): A Perspective Is COVID-19 receiving ADE from other coronaviruses Susceptibility of the Elderly to SARS-CoV-2 Infection: ACE-2 Overexpression, Shedding, and Antibody-dependent Enhancement (ADE) Similarities and Evolutionary Relationships of COVID-19 and Related Viruses. Preprints Identification of Epitopes on SARS-CoV Nucleocapsid Protein that Induce the Cross-or Specific-Reactivity among SARS-CoV, HCoV-OC43 and HCoV-229E Effectiveness of convalescent plasma therapy in severe COVID-19 patients Proc. Natl. Acad. Sci First infection by all four non-severe acute respiratory syndrome human coronaviruses takes place during childhood This study was supported by research grants from the Natural Science The authors declare that there are no conflict of interests. YZ and NW contributed to data analysis, graphics and writing the paper. YZ, NW, MY, LW and LL contributed to data collection and graphics development. JL and XT contributed to editing the paper. No date are available.This article is protected by copyright. All rights reserved.