Temporal Evolution of Humoral Response in Haemodialysis Patients Vaccinated With Two Doses of CHADOX1-S Vaccine

ABSTRACT

BACKGROUND AND AIMS Patients on long term haemodialysis have been found to be more vulnerable to COVID-19 infection with greater severity of infection and mortality rates. Vaccination is instrumental in preventing morbidity and mortality in this group. The study was conducted to evaluate the humoral response of vaccination in patients on long term haemodialysis and its evolution over time. METHOD The study was conducted between March 2021 and December 2021. It included 59 patients who received two doses of ChAdOx1-S vaccine. Demographic data was collected and antibody level against the S1 subunit of SARS-CoV-2 spike protein antigen was measured 4 weeks and 26 weeks after the administration of second dose. The patients were divided into 2 groups based on time interval between the two doses (Group I up to 6 weeks and Group II >6 weeks). RESULTS The mean age of the patients was 62.57 years. Out of 59 patients, 38 (64.40%) were males. 31 patients (52.54%) had history of diabetes mellitus (DM) and 7 (11.86%) had history of COVID-19 infection at least 3 months prior to vaccination (Table 1). Four weeks after the administration of second dose, antibodies to SARS-CoV-2 spike protein were present in 53 (89.83%) patients. 85.29% patients (29 out of 34) in group I and 96% patients (24 out of 25) in group II had detectable antibodies. There was a wide variation between the anti-spike antibody levels in the patients, ranging from 0.4 to as high as 18 933 U/mL (Figure 1) and the levels remained high even 26 weeks after the second dose of the vaccine. Antibodies to SARS-CoV-2 spike protein were present in 49 (92.45%) patients out of the total 53 patients in whom 26 weeks had elapsed after second dose of vaccination. 91.17% patients (31 out of 34) in group I and 94.7% (18 out of 19) in group II had detectable antibodies after 26 weeks of receiving second dose of the vaccine.Table 1. CONCLUSION The study provides evidence that two doses of ChAdOx1-S vaccine generate good antibody response in majority of patients on long-term haemodialysis. It is sustained at 26 weeks post second dose of vaccine. Increasing the time interval between two doses of the vaccine lead to better humoral response. The antibody levels decrease over time necessitating the administration of booster doses.