Objective The aim of the study was to investigate efficacy and safety of convalescent plasma (CP) transfusion in a group of high-risk COVID-19 patients. Methods This prospective study included 204 patients from a single tertiary-care hospital, hospitalized with COVID-19, of whom 102 were treated with CP administration and standard care (PG) and 102 others who received standard care only (CG). The CG was selected from 336 hospitalized patients using the propensity score matching (PSM) technique using age, MEWS score, and comorbidities. The primary outcome was mortality rate; secondary outcomes were the requirement of ventilator, length of ventilator need, length of intensive care unit (ICU) stay, and length of overall hospital confinement. Additionally, parameters predicting death in COVID-19 patients were identified. Results Findings confirmed a significantly lower mortality rate in the PG versus the CG (13.7% vs. 34.3 %, p = 0.001) and a significant difference in cumulative incidence of death between the two groups ( p < 0.001). CP treatment was associated to lower risk of death ( OR = 0.25 CI 95 [0.06; 0.91], p = 0.041). There were no significant differences in ICU stay, ventilator time, and hospitalization time between the two groups. Conclusions A significantly lower mortality rate was observed in the group of patients treated with CP. Age, presence of cardiac insufficiency, active cancer, requirement of ventilator, and length of hospitalization were significantly increasing the risk of death in both groups. Our study shows, that CP brings better outcomes when administrated in the earlier stage of high-risk COVID-19 disease.

Introduction:The aim of this study was to investigate the persistence of SARS-CoV-2 neutralizing antibodies (NAbs) one year after contracting COVID-19. Material and methods:The study included 38 patients -34 men and 4 women -suffering from COVID-19 between March 15 and May 26, 2020. The median age in the group was 31 years, ranging from 22 to 67 years. The levels of neutralizing antibodies were measured at three time-points -baseline, 6 months, and 12 months. The primary endpoint was a post-infection positive result for NAbs (> 15 AU/ml; Liaison SARS-CoV-2 S1/S2 IgG quantitative test) 12 months after infection.Results: The median level of NAbs after 12 months was 26.5 AU/ml. At the end of observation (12 months), 21 of the 38 patients had a NAb level of >15 AU/ml (positive). The median antibody halflife was 5.8 months.Conclusions: A high percentage of the patients maintained positive levels of antibodies 6 and 12 months after COVID-19 infection. The dynamics of the antibody level decline suggests the need for booster vaccination at least once a year.