Seroprevalence of SARS-CoV-2 in Croatian solid-organ transplant recipients

Abstract

Introduction The data on the coronavirus disease (COVID-19) in solid-organ transplant recipients (SOTRs) in Croatia is unknown. The aim of this study was to analyze the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Croatian SOTRs. Materials and methods From 7 September to 27 November 2020 (beginning of the second COVID-19 pandemic wave), a cross-sectional screening for COVID-19 was performed in the adult outpatient liver (LTRs; N = 280) and kidney transplant recipients (KTRs; N = 232). Serum samples were initially tested for SARS-CoV-2 IgG antibodies using a commercial enzyme-linked immunosorbent assay (ELISA; Vircell Microbiologists, Granada, Spain). All positive samples were confirmed using a virus neutralization test (VNT). Data on risk exposure and COVID-19 related symptoms were collected using a questionnaire. Results The transplanted cohort’s seroprevalence detected by ELISA and VNT was 20.1% and 3.1%, respectively. Neutralizing (NT) antibodies developed in 15.6% of anti-SARS-CoV-2 ELISA IgG positive SOTRs. The difference in seropositivity rates between LTRs and KTRs was not statistically significant (ELISA 21.1% vs . 19.0%, P = 0.554; VNT 3.6% vs . 2.6%, P = 0.082). Overall VNT positivity rates were higher in patients who reported participation in large community events (5.9% vs . 1.0%; P = 0.027) as well as in patients who reported COVID-19 related symptoms in the past six months. In addition, symptomatic VNT positive patients showed significantly higher (P = 0.031) NT antibody titers (median 128, interquartile range (IQR) = 32-128) compared to asymptomatic patients (median 16, IQR = 16-48). Conclusions This study showed that 15.6% of anti-SARS-CoV-2 ELISA positive Croatian SOTRs developed NT antibodies indicating protective immunity. Further studies are needed to determine the dynamic of NT antibodies and COVID-19 immunity duration in immunocompromised populations such as LTRs and KTRs.

Emerging Trends in the Epidemiology of COVID-19: The Croatian ‘One Health’ Perspective

“…Overall VNT positivity rates were higher in patients who reported participation in large community events (5.9% vs. 1.1%; p = 0.027), while no significant difference was detected in the seroprevalence rate regarding received blood products (3.0% vs. 1.6%; p = 0.553) and travelling habits (5.3% vs. 1.1%; p = 0.085). In addition, symptomatic VNT-positive patients showed significantly higher NT antibody titers (median 128, IQR = 32-128) compared to asymptomatic patients (median 16, IQR = 16-48) [18]. Compared to the general population tested after the first wave, the prevalence of NT antibodies was slightly higher in SOTRs (3.1% vs. 2.2%), demonstrating the development of protective immunity despite impaired immunological status.…”

Human coronaviruses in the "One Health" context

“…The seropositivity rates detected by enzyme-linked immunosorbent assay varied from 2% to 11.1% and 8.8% to 25.1% after the first and second waves, respectively. The prevalence of NT antibodies was 2.2-5.5% after the first wave and 2.6-18.2% after the second pandemic wave [42][43][44][45][46][47][48][49] . In a metaanalysis by Rostami et al [50] (2020) on SARS-CoV-2 seroprevalence worldwide, almost 400,000 people from 23 countries were included with seroprevalence rates in the general population ranging from 0.37% to 22.1% (pooled estimate of 3.38%).…”