Goal of this study is to evaluate the seroprevalence of anti-SARS-CoV-2 antibodies in patients after kidney transplantation who are one of the risk groups for the severe course of the infection and map the progression of the virus throughout this specific part of population, which is also important for possible future epidemics. We will evaluate the seroprevalence of anti-SARS-CoV-2 antibodies according to age and gender. We will compare seroprevalence in all measured antibodies types and we will also assess the development of antibodies level in positive patients.

The Czech Republic (Central Europe region) is one of the most affected countries in the World by COVID 19 pandemic. By 1st of March 2021, the SARS-COV-2 virus infection was proven in the Czech Republic in 1 247 051 thousand people, which is 11.7% of the population (11 627 per 100 000, in the USA 8743/100 000, in the UK 6300/100 000, in the Germany 2879/100 000, France 5379/100 000). The rapidly increasing number of people infected in October 2020 have led to adoption of strict countrywide epidemic measures, which are still largely ongoing. During first 2 months of 2021 was still serious spread of the virus in population with increasing numbers of infected persons.

The SARS-CoV-2 virus can be detected in the body by several ways. The presence of the virus can be directly confirmed by RT-PCR or by determination of viral antigen from a swab from the nasopharynx, throat, direct examination of sputum or aspirate from bronchoscopy, or rectum. Indirect methods of virus detection include the determination of antibodies in the blood. Antibodies can target several structures of the virus: spike protein (S), envelope, membrane or nucleocapsid (NP). The S protein is composed of S1 and S2 subunit. The S1 subunit contains receptor-binding domain (RBD) which is necessary for interaction and entering human cells. In practice, IgG, IgM and IgA antibodies against RBD and NP are usually detected.2,3 With regard of serious development of the COVID 19 epidemic situation in the Czech Republic, we decided to do this prevalence study. Our goal is to evaluate the seroprevalence of anti-SARS-CoV-2 antibodies in patients after kidney transplantation which is also important for possible future epidemics.

Inclusion Criteria:

• Age ≥ 18
• Recipient of a transplanted kidney
• Planned visit to the outpatient nephrology clinic of University Hospital Ostrava, Czech Republic, between 1.5. and 30.7.2021 for enrolment
• Planned blood collection and available results of blood tests from planned inspections from 18.1.2021.
• Signed consent to the use of anonymous data for scientific purposes and publications.

Exclusion Criteria:

• disagreement with participation in the study and data analysis

Patients after any kidney transplantation, monitored regularly in the nephrology clinic of the University Hospital Ostrava.