Background Patients with end-stage kidney disease receiving maintenance hemodialysis (HD) are at increased risk for mortality after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) compared with the general population. However, it is currently unknown whether the long-term SARS-CoV-2 humoral and cellular immune responses in patients receiving HD are comparable to individuals with normal kidney function. Method The prospective cohort study included 24 patients treated with maintenance HD and 27 non-renal controls with confirmed history of coronavirus disease (COVID-19). In all participants the levels of specific IgG were quantified at three timepoints: 10, 18, and 26 weeks from disease onset. In a subgroup of patients, specific T-cell responses were evaluated. Results The seropositivity rate declined in controls over time and was 85% and 70.4% at weeks 18 and 26, respectively. All HD patients remained seropositive over the study period. Seropositivity rate at week 26 was greater among patients receiving HD: RR = 1.4 [95%CI: 1.17–1.94] (reciprocal of RR = 0.7 [95% CI: 0.52–0.86]), p = 0.0064. In both groups, IgG levels decreased from week 10 to week 26, but antibodies vanished more rapidly in controls than in HD group (ANOVA p = 0.0012). The magnitude of T-cell response was significantly lower in controls than in HD patients at weeks 10 ( p = 0.019) and 26 ( p = 0.0098) after COVID-19 diagnosis, but not at week 18. Conclusion Compared with non-renal adults, patients receiving HD maintain significant long-term humoral and cellular immune responses following natural COVID-19.

Background and Aims We aimed to compare the dynamics of humoral and cellular immunity caused by natural COVID-19 or vaccination against of SARS-CoV-2 with Gam-COVID-Vac (Sputnik V) vaccine in patients, receiving maintenance hemodialysis (HD). Method Data were extracted from two prospective cohort studies which had investigated the long-term immune responses after SARS-CoV-2 infection (NCT 04633915) or vaccination (NCT 04805632) in patients receiving HD compared with those in healthy individuals. The group of patients after natural COVID-19 (n = 24) had confirmed history of disease, nobody of them received vaccination before and during the study period. Levels of specific IgG and T-cells were quantified in them at 2.5 and 6 months from disease onset. The group of vaccinated patients (n = 23) had been vaccinated twice with Gam-COVID-Vac vaccine and had no prior history of confirmed COVID-19. Levels of anti-SARS-CoV-2-specific IgG and T-cells were quantified at 1 month and 6 months from the second vaccine shot. IgG levels were determined using a semi-quantitative ELISA (Euroimmun, Germany) and converted to Binding Antibody Units (BAU/ml) according to the WHO International Standard. Specific T-cell responses (CD4+ and CD8+ cytotoxic T-lymphocytes) were evaluated using the TIGRA-test® (Generium, Russia). Only spike-specific T-spots were used for the analyses. Results Seropositivity rate declined over the course of the study among vaccinated patients (from 91% to 51%), however, all patients after natural COVID-19 remained seropositive over the study period. Thus, seropositivity rate at 6 months was greater in disease group: RR = 1.91 [95%CI: 1.4–3.1] (reciprocal of RR = 0.52 [95% CI: 0.32–0.72]), P = 0.0004. In both groups, IgG levels decreased over time, but antibodies disappeared more rapidly in vaccinated HD patients (analysis of variance p = 0.0374 for the “time × group” interaction) – Figure 1 (left). T-test reached positivity in 73% of vaccinated patients and 93% of patients after natural COVID-19 at the first timepoint. At the end of the study, T-test remained positive in 67% and 91% of the patients in both groups, respectively. Risk of T-test positivity rate at 6 months did not differ between groups (P = 0.133). T-spot counts remained stable over time in vaccinated patients, while tended to increase in patients after COVID-19 to the end of the follow-up. Differences in dynamics in these two groups were statistically significant (analysis of variance p = 0.0293 for the “time × group” interaction) – Fig.1 (right). Conclusion Patients receiving HD maintain more sustainable humoral immune responses after natural COVID-19 disease than after complete vaccination with Gam-COVID-Vac vaccine. Specific SARS-CoV-2 IgG antibodies declines faster in vaccinated patients than in patients after COVID-19 over 6-month period. Cellular immunity remains stable in both groups increasing by the 6-months period among those who had natural COVID-19.

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Background The aim of the study was to assess the prevalence of seropositive status for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-IgA, -IgM, and -IgG; its dynamics in connection with restrictive measures during the coronavirus disease (COVID-19) pandemic; and the quantitative dynamics of antibody levels in the population of St. Petersburg, Russia. Methods From May to November 2020, a retrospective analysis of Saint Petersburg State University Hospital laboratory database was performed. The database included 158,283 test results of 87,067 patients for SARS-CoV-2 detection by polymerase chain reaction (PCR) and antibody detection of SARS-CoV-2-IgA, -IgM, and -IgG. The dynamics of antibody level was assessed using R v.3.6.3. Results The introduction of a universal lockdown was effective in containing the spread of COVID-19. The proportion of seropositive patients gradually decreased; approximately 50% of these patients remained seropositive for IgM after 3–4 weeks; for IgG, by follow-up week 22; and for IgA, by week 12. The maximum decrease in IgG and IgA was observed 3–4 months and 2 months after the detection of the seropositive status, respectively. Conclusions The epidemiological study of post-infection immunity to COVID-19 demonstrates significant differences in the dynamics of IgA, IgM, and IgG seropositivity and in PCR test results over time, which is linked to the introduction of restrictive measures. Both the proportion of seropositive patients and the level of all antibodies decreased in terms of the dynamics, and only approximately half of these patients remained IgG-positive 6 months post-infection.