#4843 EFFECT OF MORNING VACCINATION COMPARED WITH AFTERNOON/EVENING VACCINATION ON HUMORAL RESPONSE TO COVID-19 VACCINE IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Patients with ESKD who are undergoing hemodialysis have impaired immunogenicity to SARS-CoV-2 vaccination. Age, dialysis vintage, use of immunosuppressive drugs, serum albumin, lymphocyte count, vaccine type, and COVID-19 experience have been identified to be associated with humoral and cellular responses. A recent review highlights that vaccination responses also exhibit circadian rhythmicity. However, the benefits of vaccination in the morning compared with later times in the day among hemodialysis patients remain unclear. Therefore, we aimed to determine if morning vaccination with a COVID-19 vaccine was able to induce a higher antibody response than afternoon/evening vaccination among hemodialysis patients. Method We conducted a prospective observational study in the hemodialysis unit of Taipei Tzu Chi Hospital, Taiwan. Prevalent hemodialysis patients aged 20 years or over with no history of SARS-CoV-2 infection were eligible for enrollment. Patients were excluded if they had been vaccinated, refused vaccination, had inadequate dialysis, or declined to participate. Patients with current use of immunosuppressants were also excluded. All participants received a priming dose of ChAdOx1 nCoV-19, an adenovirus-vectored vaccine, on June 16 or 17, 2021 during the hemodialysis session. IgG antibodies to the receptor binding domain (RBD) of the S1 subunit of the spike protein of SARS-CoV-2 were measured using the AdviseDx SARS-CoV-2 IgG II assay (Abbot Laboratories, Abbott Park, IL, USA) at Day 28 and Day 56 after vaccination. The cutoff value for positivity was set at ≥50 arbitrary units per mL (AU/mL) based on manufacturer's recommendations. Multivariate logistic regression analyses were used to evaluate the relationship between time of day of vaccination and antibody response. Covariates identified by prior studies as significant predictors of vaccine response or with a P value <0.1 between responders and nonresponders were fitted. Results A total of 201 participants were included, with a male to female distribution of 52% to 48%, a mean age of 67 years, and a median dialysis vintage of 7.7 years. Among the participants, 70 were dialyzed in the morning (between 7:00 AM and 12:00 PM), 69 in the afternoon (between 12:00 and 5:00 PM), and 62 in the evening (between 5:00 and 10:00 PM). Overall, 137 (68.2%) participants developed antibodies against the SARS-CoV-2 spike protein after a single dose of ChAdOx1 nCoV-19. The median antibody level was 184.6 AU/mL. In the multivariate model, morning vaccination, age, coronary artery disease, and lymphocyte count independently predicted a humoral response at Day 28. Participants who received morning vaccination were more likely to develop seroconversion compared with those who received afternoon/evening doses (odds ratio 3.81, 95% confidence interval 1.59–9.15; P = 0.003). Anti-spike antibody titers were measured in 198 participants at Day 56. The median antibody level was 153.7 AU/mL. A significantly higher proportion of morning-vaccinated hemodialysis patients remained seropositive (odds ratio 2.54, 95% confidence interval 1.15–5.61; P = 0.021). Conclusion Our preliminary results showed that circadian rhythms might be harnessed to optimize vaccination strategies for hemodialysis patients. Future studies with larger sample size are required to validate our findings.