[Antibody Sustainability in SARS-CoV-2 Healthcare Professionals' Patient Cohort]

In this study, it was aimed to evaluate one-year follow-up of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) specific antibodies formed against the virus binding site, in a coronavirus disease-2019 (COVID-19) positive case cohort (n= 413) between the period March 2020 to December 2020 in Manisa Celal Bayar University Hospital, until July 2021. SARS-CoV-2 antibodies were determined by the chemiluminescent enzyme immunoassay (CLIA) method. Values of 1.0 and above were considered positive. Chi-square tests and Joinpoint regression analysis (version 4.7.0) were used in the statistical analyses. The mean age of the participants was 34.9 ± 9.3 and 60.2% of them were women. Between 21-30 days after the diagnosis of COVID-19, total antibody level was above the threshold value in 72.2% (n= 126) of the participants, while this rate increased to 79.1% (n= 240) in 31-60 day interval. In the following period, this rate decreased to 38.8% (n= 108) in days 211st to 240th. Antibody response could not be detected in 76 (20.7%) of 367 employees who have initially been followed up. The percentage of total antibody positivity prevalence ranged from 98.9% to 96.1% in the 31-210th day after diagnosis, in the follow-up of 291 employees whose total antibody positivity was detected after diagnosis. According to the results of the Joinpoint regression analysis, after the diagnosis of COVID-19, the curve showing the percentage of antibody positivity was broken at two points: The first breaking point was observed in 181-210th days (6-7 months) (p= 0.069), and the second breaking point was in 271-300th days (9-10 months) (p< 0.001). As a result, the highest antibody positivity rates were detected after the 30th day of the disease onset and antibody positivity was maintained in the first seven months after diagnosis; the antibody positivity rate decreased to 25% at the end of the first year.