Dynamic changes in the concentration of anti-SARS-CoV-2 antibodies within 12 months after recovery from COVID-19

Mayanskiy NA1, Brzhozovskaya EA1, Stoyanova SS1, Frolkov AV1, Lebedin YuS2
About authors

1 Pirogov Russian National Research Medical University, Moscow, Russia

2 XEMA LLC, Moscow, Russia

Correspondence should be addressed: Nikolay A. Mayanskiy
Ostrovitianova, 1, Moscow, Russia; moc.liamg@yalokin.yiksnayam

About paper

Author contribution: Mayansky NA — concept, data processing, manuscript writing; Brzhozovskaya EA — sample collection, ELISA, data processing, making illustrations; Stoyanova SS — sample collection, data processing, making illustrations; Frolkov AV — data processing, manuscript preparation; Lebedin YuS — concept, ELISA, manuscript editing.

Compliance with ethical standards: the study was approved by the Ethics Committee of the Pirogov Russian National Research Medical University (protocol № 197 dated May 21, 2020).

Received: 2022-02-01 Accepted: 2022-02-14 Published online: 2022-02-20

Generation and maintenance of immunity to SARS-CoV-2 is essential for  overcoming the pandemic of the novel coronavirus infection COVID-19. The study was aimed to assess the dynamic changes in the levels of IgG antibodies against the SARS-CoV-2 receptor-binding domain (RBD) with the use of the enzyme-linked immunosorbent assay (ELISA) kits, calibrated using the International Standard for anti-SARS-CoV-2 immunoglobulin (IS-SARS-CoV-2). The concentrations of anti-RBD-IgG were measured in the cohort of individuals, who had recovered from COVID-19, with an interval of a month for 6 months, and at a time point of 12 months, using the ELISA kits, calibrated with the use of IS-SARS-CoV-2; the results were expressed in binding antibody units (BAU) per 1 mL. A total of 97 blood serum samples, obtained from 20 individuals with SARS-CoV-2 infection, confirmed by PCR, were collected. The geometric mean titer (GMT) of anti-RBD-IgG was 433 BAU/mL (range 36-25,900 BAU/mL) within a month after the infection. The concentration of anti-RBD-IgG gradually decreased with time and reached the GMT value of 68 BAU/mL by the 12th month; anti-RBD-IgG persisted in 13 individuals (93%) out of 14, examined 12 months after the infection. The standardized quantitative serological data play a vital part in monitoring the immune response and make in easier to compare the studies, providing the basis for seeking the common serological correlate of the protective immunity to SARS-CoV-2.

Keywords: SARS-CoV-2, anti-RBD IgG, dynamic changes, concentration, BAU/mL