Results of Comparative Serological Studies of Post-Infection and Post-Vaccination Immunity Characteristics to SARS-CoV-2 in Kidney and Liver Recipients

ABSTRACT

Introduction. Immunocompromised individuals, such as kidney and liver recipients, are at high risk for a severe course of COVID-19, which explains the special interest in this category of patients in conditions of high incidence of this infection and mass vaccination with available vaccines. Purpose. To study the characteristics of humoral post-infection and post-vaccination immunity to SARS-CoV-2 in kidney and liver recipients based on qualitative and quantitative serotesting. Materials and methods. The study of characteristics of post-infection immunity was carried out in the group of immunocompromised individuals (n=213) including kidney (n=177) and liver (n=26) recipients with PCR confirmed COVID-19, while the study of post-vaccination immunity was carried out in the group of kidney (n=56) and liver (n=12) recipients immunized with Sputnik V (Russia) or Vero Cell (China). In comparative studies, a simple randomized sample was used of immunocompetent patients who recovered from COVID-19 (n=163), corresponding in age and gender to that of the recipients examined, as well as a convenient sample of immunocompetent individuals vaccinated with Sputnik V (n=257) and Vero Cell (n=160). Serotesting for the detection of IgG to S and N proteins of SARS-CoV-2 was carried out by ELISA. Reliable intervals for proportions were calculated using the Wald method. The significance of the detected differences was assessed by the χ2 (chi-square) method. Results. The paper presents data on comparative serological testing of kidney and liver recipients recovered from COVID-19. The detection rate of post-infectious IgG to N and S proteins of SARS-CoV-2 was found to be 88.1% in the group of kidney recipients, 91.3% in the group of liver recipients, and 91.7% in the group of immunocompetent individuals. At the same time, the proportion of N protein seropositive subjects in all groups of observation was lower in comparison with that to S protein, with a significant difference in the group of kidney recipients (59.9% and 86.4%, respectively, p<0.001). The overall dynamics of the decrease in proportion of seropositive individuals during the observation period up to 12 months from the onset of clinical manifestations of infection in both groups of recipients and in the group of immunocompetent individuals had common patterns, however, seroprevalence rates for IgG to N protein significantly differed over time (9–12 months from the onset of the disease) and were much higher in the group of immunocompetent individuals (p<0.001). Despite the presence of general patterns of post-infection antibody response formation, seroprevalence rates to SARS-CoV-2 and the duration of post-infection antibody persistence were slightly lower in the group of kidney recipients than in the group of liver recipients and in immunocompetent individuals. The immunological efficacy of vaccination (the proportion of individuals with post-vaccination antibodies) in the group of kidney recipients was significantly lower (p<0.001) than in the group of immunocompetent patients after both Sputnik V (68.0% and 98.8%, respectively) and Vero Cell (58.1% and 95.0%, respectively) immunization. In liver transplant recipients, there were no significant differences with immunocompetent individuals in terms of post-vaccination response. Conclusion. The data obtained indicate certain differences in characteristics of post-infection and post-vaccination antibody response due to patients' immune status. © 2022, Professionalnye Izdaniya. All rights reserved.