WCN23-0519 VACCINE RESPONSE AGAINST SARS-Cov-2 AMONG HEMODIALYSIS PATIENTS IN TWO SENEGALESE CENTERS IN 2021

Abstract

Introduction Patients with end-stage kidney disease have been among the most affected by the covid-19 pandemic. Vaccination has been imposed in several countries as the main preventive measure. We conducted this study with the aim of evaluating the immunological response to vaccination in senegalese hemodialysis patients, and therefore the effectiveness of mass vaccination in this population. Methods We conducted a prospective, cohort study, in two dialysis centers, over a period of 5 months from March 30, 2021 to August 30, 2021. All patients who had been on dialysis for more than 6 months, vaccinated against SARS-CoV2 and who were willing to participate in the study were systematically included. All included patients received 2 doses of ChAdOx1 nCoV-19/AZD1222 vaccine at 12-week intervals according to the original WHO-recommended vaccination schedule. A vaccine response was considered positive when seroconversion was observed after one dose of vaccine. Vaccine protection was judged by the absence of new COVID-19 infection confirmed by RT-PCR in patients who received a complete vaccination schedule. Results Among the 81 patients included in our study, 2.46% had detectable anti-S IgM antibodies before the first dose of vaccine, while the positivity rate was 12.34% one month after the first dose and 2.46% at M4, 1 month after the 2nd dose. Prior to vaccination, 45.68% of patients had detectable IgG anti-S antibodies, while at M1, 1 month after the first dose, 69.14% of patients were positive and at M4 59.26% of patients were. Of the 19 patients infected with Sars-cov-2 prior to vaccination, 2 (10,52%) had detectable IgM antibodies at M0, then 6 (31.58%) at M1 and 2(10.52%) at M4, while in the covid naive group there was no IgM positive subject at M0, 4(6.45%) at M1 and none at M4. Following the same trend, 17 (89.47%) of the previously infected patients had detectable IgG antibodies at M0, 18 (94.73%) at M1 and and 17 (89.47%) at M4, while in the covid naive group 20(32.26%) had detectable IgG at M0, 38 (61.29%) at M1 and 31 (50%) at M4. The seroconversion rate for IgM anti-S antibodies at M1 was 11.39% and statistically significant. At M4, the seroconversion rate compared to the pre-vaccination threshold was 2.53% and not significant. The seroconversion rate for IgG anti-S antibodies at M1 was 56.81% and statistically significant. At M4, the seroconversion rate compared to the pre-vaccination threshold was 52.27% without reaching the significance threshold. IgG-positive patients after two doses of vaccine had a mean length of dialysis of 22 months, which was significantly lower by 10 months than those who did not develop IgG. None of the other parameters studied showed a statistically significant difference between these two groups, including the number of patients with COVID19 infection before or after vaccination and the use of immunosuppressive therapy. Conclusions Vaccination is currently the main measure in the fight against covid, especially in resource limited countries. However, it appears from this study that the protection it offers in haemodialysis patients is neither definitive nor absolute, and that it can be influenced, among other things, by the time spent on dialysis. No conflict of interest