Epidemiological study using IgM and IgG antibody titers against SARS-CoV-2 in The University of Tokyo, Japan (UT-CATS)

Abstract

Introduction The worldwide pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to date. Given that some of the patients with coronavirus disease 2019 (COVID-19) are asymptomatic, antibody tests are useful to determine whether there is a previous infection with SARS-CoV-2. In this study, we measured IgM and IgG antibody titers against SARS-CoV-2 in the serum of asymptomatic healthy subjects in The University of Tokyo, Japan. Methods From June 2020, we recruited participants, who were students, staff, and faculty members of The University of Tokyo in the project named The University of Tokyo COVID-19 Antibody Titer Survey (UT-CATS). Following blood sample collection, participants were required to answer an online questionnaire about their social and health information. We measured IgG and IgM titers against SARS-CoV-2 using iFlash-SARS-CoV-2 IgM and IgG detection kit which applies a chemiluminescent immunoassay (CLIA) for the qualitative detection. Results There were 6,609 volunteers in this study. After setting the cutoff value at 10 AU/mL, 32 (0.48%) were positive for IgG and 16 (0.24%) for IgM. Of six participants with a history of COVID-19, five were positive for IgG, whereas all were negative for IgM. The median titer of IgG was 0.40 AU/mL and 0.39 AU/mL for IgM. Both IgG and IgM titers were affected by gender, age, smoking status, and comorbidities. Conclusions Positive rates of IgG and IgM titers were relatively low in our university. Serum levels of these antibodies were affected by several factors, which might affect the clinical course of COVID-19.

The Fluctuation Trend of Serum Anti-SARS-CoV-2 IgM/IgG Antibodies Seroprevalence in the Non-COVID-19 Infected Population and Correlation with Peripheral Blood Leukocyte Parameters in Beijing, China, 2021: A Real-World Study

“…However, this study is a time-series large population study, and our study focuses on the macroscopic relationship between the overall serum antibodies level and positive rate with time; thus, the results of the study may not be consistent with other studies. Finally, Serum SARS-CoV-2 IgG antibody kits used in his study are different from others used in the previous reports, and the results of the study are closely related to the cutoff values set by different manufacturers because the reagent manufacturers need to comprehensively consider the specificity and sensitivity of the detection method to set cutoff values [18,22]. Therefore, our results reflected the actual seropositivity level of IgG and the status of herd immunity of the resident population in that period.…”

Assessment of immunoglobin G (spike and nucleocapsid protein) response to COVID-19 vaccination in Palestine

“…Furthermore, the results revealed that smokers had lower levels of vaccine-induced antibodies than nonsmokers as well as an increase in IgG-N levels in smoker individuals due to the elevated susceptibility to infection, which is consistent with earlier research. 36 , 37 , 38 , 39 More research is needed into the mechanisms through which cigarette smoke decreases immunological responses to COVID-19 vaccines.…”