Characterizing Kinetics and Avidity of SARS-CoV-2 Antibody Responses in COVID-19 Greek Patients
Stavroula Labropoulou,
Niki Vassilaki,
Raphaela S. Milona,
Evangelos Terpos,
Marianna Politou,
Vasiliki Pappa,
Maria Pagoni,
Elisavet Grouzi,
Meletios A. Dimopoulos,
Andreas Mentis,
Mary Emmanouil,
Emmanouil Angelakis
Affiliations
Stavroula Labropoulou
Diagnostics Department and Public Health Laboratories, Hellenic Pasteur Institute, 11521 Athens, Greece
Niki Vassilaki
Laboratory of Molecular Virology, Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue, 11521 Athens, Greece
Raphaela S. Milona
Laboratory of Molecular Virology, Hellenic Pasteur Institute, 127 Vasilissis Sofias Avenue, 11521 Athens, Greece
Evangelos Terpos
Department of Clinical Therapeutics, School of Medicine, National and Kapodistrian University of Athens, 11528 Athens, Greece
Marianna Politou
Hematology Laboratory Blood Bank, School of Medicine, Aretaieion Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece
Vasiliki Pappa
Hematology Unit, Second Department of Internal Medicine, School of Medicine, Attikon University General Hospital, National and Kapodistrian University of Athens, 12461 Athens, Greece
Maria Pagoni
BMT Unit, Department of Hematology and Lymphomas, Evangelismos General Hospital, 10676 Athens, Greece
Elisavet Grouzi
Department of Transfusion Service and Clinical Hemostasis, “Saint Savvas” Oncology Hospital, 11522 Athens, Greece
Meletios A. Dimopoulos
Department of Clinical Therapeutics, School of Medicine, National and Kapodistrian University of Athens, 11528 Athens, Greece
Andreas Mentis
Diagnostics Department and Public Health Laboratories, Hellenic Pasteur Institute, 11521 Athens, Greece
Mary Emmanouil
Diagnostics Department and Public Health Laboratories, Hellenic Pasteur Institute, 11521 Athens, Greece
Emmanouil Angelakis
Diagnostics Department and Public Health Laboratories, Hellenic Pasteur Institute, 11521 Athens, Greece
In-depth understanding of the immune response provoked by SARS-CoV-2 infection is necessary, as there is a great risk of reinfection and a difficulty in achieving herd immunity due to a decline in both antibody concentration and avidity. Avidity testing, however, could overcome variability in the immune response associated with sex or clinical symptoms, and thus differentiate between recent and past infections. In this context, here, we analyzed SARS-CoV-2 antibody kinetics and avidity in Greek hospitalized (26%) and non-hospitalized (74%) COVID-19 patients (N = 71) in the course of up to 15 months after their infection to improve the accuracy of the serological diagnosis in dating the onset of the infection. The results showed that IgG-S1 levels decline significantly at four months (p = 0.0239) in both groups of patients and are higher in hospitalized ones (up to 2.1-fold, p < 0.001). Additionally, hospitalized patients’ titers drop greatly and are equalized to non-hospitalized ones only at a time-point of twelve to fifteen months. Antibody levels of women in total remain more stable months after infection, compared to men. Furthermore, we examined the differential maturation of IgG avidity after SARS-CoV-2 infection, showing an incomplete maturation of avidity that results in a plateau at four months after infection. We also defined 38.2% avidity (sensitivity: 58.9%, specificity: 90.91%) as an appropriate “cut-off” that could be used to determine the stage of infection before avidity reaches a plateau.
