Seroresponse to SARS-CoV-2 Vaccines among Maintenance Dialysis Patients over 6 Months

Anti-spike antibody level is associated with the risk of clinical progression among subjects hospitalized with COVID-19 pneumonia: results from a retrospective cohort study

PURPOSE

Antibodies against SARS-CoV-2 spike (anti-S) may confer protection against symptomatic COVID-19. Whether their level predicts progression among those with COVID-19 pneumonia remains unclear.

METHODS

We conducted a retrospective cohort study to assess predictors of anti-S levels and whether anti-S titer is associated with death or mechanical ventilation (MV). Adults hospitalized for COVID-19 pneumonia between July 2021 and July 2022 were enrolled if anti-S had been measured within 72 h of admission. Predictors of anti-S level were explored using multivariable quantile regression. The association between anti-S levels and 30-day death/MV was investigated via multivariable logistic regression. Analyses were stratified by vaccine status.

RESULTS

The median anti-S level was 1370 BAU/ml in 328 vaccinated and 15.5 BAU/ml in 206 unvaccinated individuals. Among the vaccinated, shorter symptom duration (p = 0.001), hematological malignancies (p = 0.002), and immunosuppressive therapy (p = 0.004) were associated with lower anti-S levels. In the unvaccinated group, symptom duration was the only predictor of anti-S levels (p < 0.001). After 30 days, 134 patients experienced death or MV. Among vaccinated individuals, higher anti-S levels correlated significantly with lower death/MV risk (per log2 increase, OR 0.88, 95%CI 0.81-0.97), irrespective of age and solid malignancies. Among unvaccinated, a marginally protective effect was observed (OR 0.86, 95%CI 0.73-1.01), independent of age, immunosuppressive therapy, and diabetes. Adjustment for monoclonal antibody treatment strengthened the association (OR 0.81, 95%CI 0.68-0.96).

CONCLUSION

This study suggests that levels of anti-S antibodies can predict critical or fatal outcomes in COVID-19 pneumonia patients, regardless of vaccination. Whether anti-S Ab could guide risk assessment and vaccination boosting merits further evaluation.

Review of clinical characteristics and mortality outcomes in patients on maintenance hemodialysis during the Omicron surge: a single center experience

BACKGROUND

This hemodialysis center experienced the pandemic from December 2022 to January 2023. Therefore, we sought to describe the clinical characteristics and mortality outcomes in hemodialysis patients during this Omicron surge.

METHODS

According to whether they are infected, they are divided into two groups: SARS-CoV-2-positive and SARS-CoV-2-negative. The SARS-CoV-2-positive group was divided into a survival group and a non-survival group for comparison.

RESULTS

366 of 457 hemodialysis patients were infected with SARS-CoV-2. The most common symptoms observed were fever (43.2%) and cough (29.8%), Followed by diarrhea (1.4%). Hemodialysis patients with hypertension were more susceptible to SARS-CoV-2 infection. The lymphocyte count, serum creatinine, serum potassium, and serum phosphorus in the SARS-CoV-2-positive group were significantly lower than those in the SARS-CoV-2-negative group. The all-cause mortality rate for infection with SARS-CoV-2 was 5.2%. Only 7 of 366 SARS-CoV-2-positive patients were admitted to the intensive care unit, but 6 of them died. Intensive care unit hospitalization rates were significantly higher in the non-survival group compared with the survival group. White blood cells count, neutrophil count, C-reactive protein, AST, and D-dimer in the non-survival group were higher than those in the survival group. The lymphocyte count, hemoglobin concentration, serum creatinine, serum albumin, serum phosphorus and parathyroid hormone in the non-survival group were lower than those in the survival group. Age > 65 years, elevated C-reactive protein and AST are independent risk factors for death. Finally, no significant difference in vaccination status was found between the SARS-CoV-2-positive group and the negative group.

CONCLUSIONS

Hemodialysis patients are at high risk for SARS-CoV-2 infection. Ensuring the adequacy of hemodialysis treatment and maintaining good physical condition of patients are the top priorities.

18-month longitudinal SARS COV-2 neutralizing antibody dynamics in haemodialysis patients receiving heterologous 3-dose vaccination (AZD-1222- AZD-1222- BNT162b2) in a lower middle income setting

BACKGROUND

Patients with chronic kidney disease on haemodialysis (HD) were given priority COVID-19 vaccination due to increased disease risk. The immune response to COVID-19 vaccination in patients on HD was diminished compared to healthy individuals in 2-dose studies. This study aimed to evaluate seroconversion rate, neutralizing antibody (nAB) levels and longitudinal antibody dynamics to 3-dose heterologous vaccination against COVID-19 in a cohort of HD patients compared to healthy controls and assess patient factors associated with antibody levels.

METHODS

This study was a case-control longitudinal evaluation of nAB dynamics in 74 HD patients compared to 37 healthy controls in a low/middle income setting. Corresponding samples were obtained from the two cohorts at time-points (TP) 1-1-month post 2nd dose of AZD1222 vaccine, TP2- 4 months post 2nd dose, TP4- 2 weeks post 3rd dose with BNT162b2 vaccine, TP5-5 months post 3rd dose and TP6-12 months post 3rd dose. Additional data is available at TP0- pre 2nd dose and TP3- 6 months post 2nd dose in HC and HD cohorts respectively. Anti-SARS-CoV-2 nAB were detected using Genscript cPassTM pseudoviral neutralization kit. Demographic and clinical details were obtained using an interviewer administered questionnaire.

RESULTS

Cohorts were gender matched while mean age of the HD cohort was 54.1yrs (vs HCs mean age, 42.6yrs, p < 0.05). Percentage seroconverted and mean/median antibody level (MAB) in the HD cohort vs HCs at each sampling point were, TP1-83.7% vs 100% (p < 0.05), MAB-450 IU/ml vs 1940 IU/ml (p < 0.0001); TP2-71.4% vs 100%, (p < 0.001), MAB- 235 IU/ml vs 453 IU/ml, (p < 0.05); TP4-95.2% vs 100% (p > 0.05), MAB-1029 IU/ml vs 1538 IU/ml (p < 0.0001); TP5-100% vs 100%, MAB-1542 IU/ml vs 1741IU/ml (p > 0.05); TP6-100% vs 100%, MAB-1961 IU/ml vs 2911 IU/ml (p > 0.05). At TP2, patients aged < 60 years (p < 0.001) were associated with maintaining seropositivity compared to patients > 60 years.

CONCLUSION

Two dose vaccination of haemodialysis patients provided poor nAB levels which improved markedly following 3rd dose vaccination, the effect of which was long- lasting with high nAB levels in both patients and controls detectable at 1 year follow-up.

Vaccination for Patients Receiving Dialysis

Vaccinating patients receiving dialysis may prevent morbidity and mortality in this vulnerable population. The National Forum of End-Stage Renal Disease Networks (the Forum) published a revised vaccination toolkit in 2021 to update evidence and recommendations on vaccination for patients receiving dialysis. Significant changes in the last 10 years include more data supporting the use of a high-dose influenza vaccine, the introduction of the Heplisav-B vaccine for hepatitis B, and changes in pneumococcal vaccines, including the approval of the PCV15 and PCV20 to replace the PCV13 and PPSV23 vaccines. Additional key items include the introduction of vaccines against severe acute respiratory syndrome coronavirus 2, the virus that causes coronavirus disease 2019 (COVID-19), and a new vaccine to prevent respiratory syncytial virus disease. Historically, influenza and pneumococcal vaccinations were routinely administered by dialysis facilities, and because of possible risks of hematogenous spread of hepatitis B, dialysis providers often have detailed hepatitis B vaccine protocols. In March 2021, COVID-19 vaccines were made available for dialysis facilities to administer, although with the end of the public health emergency, vaccine policies by dialysis facilities against COVID-19 remains uncertain. The respiratory syncytial virus vaccine was authorized in 2023, and how dialysis facilities will approach this vaccine also remains uncertain. This review summarizes the Forum's vaccination toolkit and discusses the role of the dialysis facility in vaccinating patients to reduce the risk of severe infections.

Efficacy of vaccination against the SARS-CoV-2 virus in patients with chronic kidney disease on hemodialysis

SARS-CoV-2 has had a great impact on world health, patients on hemodialysis have a higher rate of infection and death due to COVID-19. Vaccination is important to control infection and improve the prognosis of infected patients. To describe the efficacy of vaccination against SARS-CoV-2 in Chilean patients on hemodialysis during the year 2021. Retrospective observational study. A total of 9,712 clinical records were reviewed. Data were presented as summary measures. Fisher's exact test, Mann-Whitney U test, and multivariate logistic regression were used for the analysis. Risk and survival analysis were calculated, considering a statistical significance of less than 0.05. The average age of the patients attended was 61.5 ± 14.6 years. Average time on dialysis 67.6 months and 35.0% diabetic. 93.2% of patients were vaccinated against SARS-CoV-2, 70.7% of them received booster doses. The risk of infection was higher for those who received one or no dose, compared to those who received booster doses against SARS-CoV-2: OR = 252.46 [165.13; 401.57]. Of the infected patients, 15.7% died from COVID-19. The risk of death was higher in unvaccinated or single-dose patients compared to those vaccinated with two doses: OR = 2.64 [2.23; 3.12]. Patients with two doses and a booster had a longer survival compared to those who received one or no dose of vaccination against SARS-CoV-2 (p < .05). The vaccination in Chile, which started in February 2021, has demonstrated that booster doses against SARS-CoV-2 significantly reduced the risk of infection, hospitalization, and death due to COVID-19 in patients on hemodialysis.

Serial SARS-CoV-2 Antibody Titers in Vaccinated Dialysis Patients: Prevalence of Unrecognized Infection and Duration of Seroresponse

Rationale & Objective

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections are likely underdiagnosed, but the degree of underdiagnosis among patients receiving maintenance dialysis is unknown. The durability of the immune response after the third vaccine dose in this population also remains uncertain. This descriptive study tracked antibody levels to (1) assess the rate of undiagnosed infections and (2) characterize seroresponse durability after the third dose.

Study Design

Retrospective observational study.

Setting & Participants

SARS-CoV-2-vaccinated patients receiving maintenance dialysis through a national dialysis provider. Immunoglobulin G spike antibodies [anti-spike immunoglobulin (Ig) G] titers were assessed monthly after vaccination.

Exposures

Two and 3 doses of SARS-CoV-2 vaccine.

Outcomes

Undiagnosed and diagnosed SARS-CoV-2 infections; anti-spike IgG titers over time.

Analytical Approach

Undiagnosed SARS-CoV-2 infections were identified as an increase in anti-spike IgG titer of ≥100 BAU/mL, not associated with receipt of vaccine or diagnosed SARS-CoV-2 infection (by polymerase chain reaction test or antigen test). In descriptive analyses, anti-spike IgG titers were followed over time.

Results

Among 2,703 patients without previous coronavirus disease 2019 (COVID-19) who received an initial 2-dose vaccine series, 271 had diagnosed SARS-CoV-2 infections (3.4 per 10,000 patient-days) and 129 had undiagnosed SARS-CoV-2 infections (1.6 per 10,000 patient-days). Among 1,894 patients without previous COVID-19 who received a third vaccine dose, 316 had diagnosed SARS-CoV-2 infections (7.0 per 10,000 patient-days) and 173 had undiagnosed SARS-CoV-2 infections (3.8 per 10,000 patient-days). In both cohorts, anti-spike IgG levels declined over time. Of the initial 2-dose cohort, 66% had a titer of ≥500 BAU/mL in the first month, with 24% maintaining a titer of ≥500 BAU/mL at 6 months. Of the third dose cohort, 95% had a titer of ≥500 BAU/mL in the first month after the third dose, with 77% maintaining a titer of ≥500 BAU/mL at 6 months.

Limitations

The assays used had upper limits.

Conclusions

Among patients receiving maintenance dialysis, about 1 in every 3 SARS-CoV-2 infections was undiagnosed. Given this population's vulnerability to COVID-19, ongoing infection control measures are needed. A 3-dose primary mRNA vaccine series optimizes seroresponse rate and durability.

Plain-Language Summary

Patients receiving maintenance dialysis have been particularly vulnerable to COVID-19. Using serially measured antibodies, we found that a substantial proportion (about one-third) of SARS-CoV-2 infections among this population had been missed, both among those who had completed a 2-dose vaccine series and among those who had received a third vaccine dose. Such missed infections likely had only mild or minimal symptoms, but this failure to recognize all infections is concerning. Furthermore, vaccines have been effective among patients receiving dialysis, but our study additionally shows that the immune response wanes over time, even after a third dose. There is therefore a role for ongoing vigilance against this highly transmissible infection.

Lessons from SENCOVAC: A prospective study evaluating the response to SARS-CoV-2 vaccination in the CKD spectrum

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has negatively impacted on patients of the whole CKD spectrum, causing high rates of morbi-mortality. SARS-CoV-2 vaccines opened a new era, but patients with CKD (including kidney transplant, hemodialysis and peritoneal dialysis) were systematically excluded from pivotal clinical trials. The Spanish Society of Nephrology promoted the multicentric national SENCOVAC study aimed at assessing immunological responses after vaccination in patients with CKD. During the first year after vaccination, patients with non-dialysis CKD and those on hemodialysis and peritoneal dialysis presented good anti-Spike antibody responses to vaccination, especially after receiving the third and fourth doses. However, kidney transplant recipients presented suboptimal responses after any vaccination schedule (initial, third and fourth dose). Especially worrisome is the situation of a patients with a persistently negative humoral response that do not seroconvert after boosters. In this regard, monoclonal antibodies targeting SARS-CoV-2 have been approved for high-risk patients, although they may become obsolete as the viral genome evolves. The present report reviews the current status of SARS-CoV-2 vaccination in the CKD spectrum with emphasis on lessons learned from the SENCOVAC study. Predictors of humoral response, including vaccination schedules and types of vaccines, as well as the integration of vaccines, monoclonal antibodies and antiviral agents are discussed.

Comparison of Humoral Response between Third and Fourth Doses of COVID-19 Vaccine in Hemodialysis Patients

Dialysis patients are more likely to die or become hospitalized from coronavirus disease 2019 (COVID-19). Currently, only a few studies have evaluated the efficacy of a fourth booster vaccination in hemodialysis (HD) patients and there is not enough evidence to recommend for or against a fourth booster vaccination. This study compared the humoral response and disease severity of patients on HD who received either three or four doses of COVID-19 vaccine. A total of 88 patients were enrolled. Humoral response to vaccination was measured by quantifying immunoglobulin G levels against the receptor binding domain of SARS-CoV-2 (anti-RBD IgG) at five different times and plaque reduction neutralization tests (PRNT) at two different times after vaccination over a period of 18 months. Antibody levels were measured at approximately two-month intervals after the first and second dose, then four months after the third dose, and then one to six months after the fourth dose of vaccine. PRNT was performed two months after the second and four months after the third dose of vaccine. We classified patients into four groups according to the number of vaccine doses and presence of COVID-19 infection. Severe infection was defined as hospital admission for greater than or equal to two weeks or death. There was no difference in antibody levels between naïve and infected patients except after a fourth vaccination, which was effective for increasing antibodies in infection-naïve patients. Age, sex, body mass index (BMI), dialysis vintage, and presence of diabetes mellitus (DM) did not show a significant correlation with antibody levels. Four patients who experienced severe COVID-19 disease tended to have lower antibody levels prior to infection. A fourth dose of SARS-CoV-2 vaccine significantly elevated antibodies in infection-naïve HD patients and may be beneficial for HD patients who have not been previously infected with SARS-CoV-2 for protection against severe infection.

Antibody response in patients undergoing chronic hemodialysis post-severe acute respiratory syndrome coronavirus 2 vaccination: A prospective observational study

Vaccination is important for patients undergoing hemodialysis (HD) to prevent coronavirus disease 2019 (COVID-19) infection since they are more vulnerable. However, they exhibit a weak response to vaccines, underscoring the importance of understanding whether antibodies are sufficiently produced and their durability post-COVID-19 vaccination. This prospective observational study assessed the antibody response of Korean patients undergoing HD for 1 year. We compared the antibody responses of patients undergoing HD to the COVID-19 vaccine with those of healthy volunteers from 2021 to 2022. The patient and control groups received 2 doses of ChAdOx1 nCoV-19 and mRNA-1273, respectively. Immunoglobulin G (IgG) and neutralizing antibody levels were measured weeks or months apart after 2 doses for 1 year using enzyme-linked immunosorbent and fluorescence-based competitive severe acute respiratory syndrome coronavirus 2 neutralizing assays, respectively. We analyzed the third dose's effect on the patient group by categorizing the group into patients who received the third dose and those who did not since it was initiated midway through the study. In the control group, we enrolled participants who had completed 3 doses of mRNA-1273 since almost all participants received the third dose. Thirty-two patients undergoing HD and 15 healthy participants who received 2 doses of ChAdOx1 nCoV-19 and 3 of mRNA-1273, respectively, were enrolled. Although antibody production was weaker in the patient group than in the control group (P < .001), patients showed an increase in IgG levels (0.408 ± 0.517 optical density (OD) pre-vaccination, 2.175 ± 1.241 OD in patients with 2 doses, and 2.134 ± 1.157 OD in patients with 3 doses 1 year after the second dose) and neutralizing antibodies (23 ± 8% pre-vaccination, 87 ± 23% in patients with 2 doses, and 89 ± 18% in patients with 3 doses 1 year after the second dose) post-vaccination (P < .001). In the patient group, 19 patients received a third dose (BNT162b2 or mRNA-1273); however, it did not increase the antibody levels (P = 1.000). Furthermore, the antibodies produced by the vaccination did not wane until 1 year. Two doses of vaccination resulted in a significant antibody response in patients undergoing HD, and antibody levels did not wane until 1 year.

Dialysis modality, humoral response to vaccine, and SARS-CoV-2 infection risk: Comparative prospective evaluation

BACKGROUND

COVID-19 vaccinations have a central role in decreasing severe SARS-CoV-2 disease complications. This study investigated the long-term humoral immune response to BNT162b2 vaccine among hemodialysis (HD) versus peritoneal dialysis (PD) patients, and their relative risk for COVID-19 infection.

METHODS

This prospective, observational study included maintenance HD and PD patients who had received at least two BNT162b2 vaccine doses. Levels of antibodies targeting SARS-CoV-2 spike protein were measured 6 and 12 months after the first vaccine dose, and 2-3 weeks after the third and fourth vaccine doses. Patients were divided according to dialysis modality (HD or PD). Humoral response was evaluated at different time points among different vaccine regimens (two vs. three vs. four doses of vaccine). An adjusted multivariate model was used to assess cumulative risk for SARS-CoV-2 infection.

RESULTS

Eighty-seven HD and 36 PD patients were included. Among them, 106 (86%) received at least three vaccine doses. Both HD and PD patients demonstrated marked increases in humoral response 2-3 weeks after the third dose (mean anti-S antibody increased from 452 ± 501 AU/mL to 19,556 ± 14,949 AU/mL, p < 0.001). By 6 months after the third dose, antibody titers had declined significantly (mean anti-S antibody 9841 ± 10,493 AU/mL, p < 0.001). HD patients had higher risk for SARS-CoV-2 infection than PD patients (OR 4.4 [95% CI 1.4-13.6], p = 0.006). In multivariate analysis, the most important predictor for SARS-CoV-2 infection was dialysis modality.

CONCLUSION

This study found a high antibody response rate after the third and fourth doses of BNT162b2 vaccine among dialysis patients. Hemodialysis as dialysis modality is an important predictor of COVID-19 infection, despite similar humoral responses to vaccine in peritoneal dialysis.

COVID-19 Vaccination Among Patients Receiving Maintenance Renal Replacement Therapy: Immune Response, Real-World Effectiveness, and Implications for the Future

Chronic kidney disease affects more than 800 million people worldwide and often progresses to end-stage renal disease, which requires maintenance dialysis. Patients receiving dialysis are at higher risk for severe respiratory infections, including SARS-CoV-2 (the causative agent of COVID-19). In addition, many patients who receive dialysis also receive immunosuppressive treatments for conditions such as systemic vasculitis, systemic lupus erythematosus, or malignancies. Many studies have shown that while mRNA COVID-19 vaccines induce some level of immune response in patients receiving dialysis, the magnitude of response is often lower than that of healthy individuals, and responses rapidly wane. Importantly, the risk of COVID-19-related hospitalization and mortality for patients receiving dialysis is 4- to 8-fold higher compared with the general population. In this article, we summarize recent immunogenicity and real-world outcomes of COVID-19 mRNA vaccination among patients receiving dialysis, with a focus on the 3-dose extended primary series and additional (fourth) doses.

Antibody response to COVID-19 vaccination in patients on chronic hemodialysis

Purpose

Since patients on hemodialysis (HD) are known to be vulnerable to coronavirus disease 2019 (COVID-19), many studies were conducted regarding the effectiveness of the COVID-19 vaccine in HD patients in Western countries. Here, we assessed antibody response of HD patients for 6 months post-vaccination to identify the duration and effectiveness of the COVID-19 vaccine in the Asian population.

Materials and Methods

We compared antibody response of the COVID-19 vaccine in HD patients with healthy volunteers. Patient and control groups had two doses of ChAdOx1 nCoV-19 and mRNA-1273, respectively. Immunoglobulin G (IgG) was measured before vaccination, 2 weeks after the first dose, 2 and 4 weeks, 3 and 6 months after the second dose. Neutralizing antibody was measured before vaccination and at 2 weeks, 3 and 6 months after second dose. Since the third dose was started in the middle of the study, we analyzed the effect of the third dose as well.

Results

Although antibody production was weaker than the control group (n=22), the patient group (n=39) showed an increase in IgG and neutralizing antibody after two doses. And, 21/39 patients and 14/22 participants had a third dose (BNT162b2 or mRNA-1273 in the patient group, mRNA-1273 in the control group), and it did not affect antibody response in both group. Trend analysis showed IgG and neutralizing antibody did not decrease over time. Age, sex, and HD vintage did not affect antibody production in HD patients. Patients with higher body mass index displayed better seroresponse, while those on immunosuppressants showed poor seroresponse.

Conclusion

Two doses of vaccination led to significant antibody response in HD patients, and the antibody did not wane until 6 months.

Durable Anti-SARS-CoV-2 Antibody Response after mRNA-1273 Booster in Peritoneal Dialysis Patients during the Omicron Wave

Anti-SARS-CoV-2 vaccination of dialysis patients has been proven to be safe and effective to reduce COVID-19-related morbidity and mortality. However, data on the durability of anti-SARS-CoV-2 antibodies post-vaccination in peritoneal dialysis (PD) patients are scarce. In this prospective single-center cohort study we measured anti-SARS-CoV-2 RBD antibodies 3 and 6 months after the 3rd dose of the mRNA-1273 vaccine in 27 adult PD patients and recorded breakthrough infections. Furthermore, in a mixed model analysis, we analyzed potential factors influencing the humoral response following vaccination. Anti-SARS-CoV-2 RBD antibody levels declined from 21,424 BAU/mL at 1 month to 8397 BAU/mL at 3 months and to 5120 BAU/mL at 6 months after the 3rd dose, but remained higher than pre-3rd dose levels (212 BAU/mL). Eight patients (29.6%) were infected with SARS-CoV-2 within six months from the 3rd dose during the Omicron wave. Previous high antibody levels, high glomerular filtration rate (GFR) and low Davies Comorbidity Score were associated with higher anti-SARS-CoV-2 antibody levels after the booster. In conclusion, PD patients exhibited a robust and durable humoral response after a third dose of the mRNA-1273 vaccine. A high GFR and low comorbidity as well as previous high antibody levels predicted a better humoral response to vaccination.

What has vaccination against COVID-19 in CKD patients taught us?

Effective vaccination strategies are of crucial importance to protecting patients who are vulnerable to infections, such as patients with chronic kidney disease. This is because the decreased efficiency of the immune system in chronic kidney disease impairs vaccine-induced immunisation. COVID-19 has prompted investigation of the immune response to SARS-CoV-2 vaccines in chronic kidney disease and in kidney transplant recipients in an effort to improve efficacy. The seroconversion rate after two vaccine doses is reduced, especially in kidney transplant recipients. Furthermore, although the seroconversion rate in chronic kidney disease patients is as high as in healthy subjects, anti-spike antibody titres are lower than in healthy vaccinated individuals, and these titres decrease rapidly. Although the vaccine-induced anti-spike antibody titre correlates with neutralising antibody levels and with protection against COVID-19, the protective prognostic significance of their titre is decreased due to the emergence of SARS-CoV-2 variants other than the Wuhan index virus against which the original vaccines were produced. Cellular immunity is also relevant, and because of cross-reactivity to the spike protein, epitopes of different viral variants confer protection against newly emerging variants of SARS-CoV-2. A multi-dose vaccination strategy is the most effective way to obtain a sufficient serological response. In kidney transplant recipients, a 5-week discontinuation period from antimetabolite drugs in concomitance with vaccine administration may also increase the vaccine's efficacy. The newly acquired knowledge obtained from COVID-19 vaccination is of general interest for the success of other vaccinations in chronic kidney disease patients.

Effectiveness of Three Doses of mRNA COVID-19 Vaccines in the Hemodialysis Population during the Omicron Period

BACKGROUND

Coronavirus disease 2019 (COVID-19) vaccine effectiveness studies in the hemodialysis population have demonstrated that two doses of mRNA COVID-19 vaccines are effective against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe complications when Alpha and Delta were predominant variants of concern. Vaccine effectiveness after a third dose versus two doses for preventing SARS-CoV-2 infection and severe COVID-19 in the hemodialysis population against Omicron is not known.

METHODS

We conducted a retrospective cohort study in Ontario, Canada, between December 1, 2021, and February 28, 2022, in the maintenance hemodialysis population who had received two versus three doses of mRNA COVID-19 vaccines. COVID-19 vaccination, SARS-CoV-2 infection, and related hospitalization and death were determined from provincial databases. The primary outcome was the first RT-PCR confirmed SARS-CoV-2 infection, and the secondary outcome was a SARS-CoV-2-related severe outcome, defined as either hospitalization or death.

RESULTS

A total of 8457 individuals receiving in-center hemodialysis were included. At study initiation, 2334 (28%) individuals received three doses, which increased to 7468 (88%) individuals by the end of the study period. The adjusted hazard ratios (aHR) for SARS-CoV-2 infection (aHR, 0.58; 95% confidence interval [CI], 0.50 to 0.67) and severe outcomes (hospitalization or death) (aHR, 0.40; 95% CI, 0.28 to 0.56) were lower after three versus two doses of mRNA vaccine. Prior infection, independent of vaccine status, was associated with a lower risk of reinfection, with an aHR of 0.44 (95% CI, 0.27 to 0.73).

CONCLUSIONS

Three-dose mRNA COVID-19 vaccination was associated with lower incidence of SARS-CoV-2 infection and severe SARS-CoV-2-related outcomes during the Omicron period compared with two doses.

Early Experience with Modified Dose Nirmatrelvir/Ritonavir in Dialysis Patients with Coronavirus Disease 2019

BACKGROUND

Nirmatrelvir/ritonavir was approved for use in high-risk outpatients with coronavirus disease 2019 (COVID-19). However, patients with severe CKD were excluded from the phase 3 trial, and the drug is not recommended for those with GFR <30 ml/min per 1.73 m 2 . On the basis of available pharmacological data, we developed a modified low-dose regimen of nirmatrelvir/ritonavir 300/100 mg on day 1, followed by 150/100 mg daily from day 2 to 5. In this study, we report our experience with this modified dose regimen in dialysis patients in the Canadian province of Ontario.

METHODS

We included dialysis patients who developed COVID-19 and were treated with the modified dose nirmatrelvir/ritonavir regimen during a 60-day period between April 1 and May 31, 2022. Details of nirmatrelvir/ritonavir use and outcomes were captured manually, and demographic data were obtained from a provincial database. Data are presented with descriptive statistics. The principal outcomes we describe are 30-day hospitalization, 30-day mortality, and required medication changes with the modified dose regimen.

RESULTS

A total of 134 dialysis patients with COVID-19 received nirmatrelvir/ritonavir during the period of study. Fifty-six percent were men, and the mean age was 64 years. Most common symptoms were cough and/or sore throat (60%). Medication interactions were common with calcium channel blockers, statins being the most frequent. Most patients (128, 96%) were able to complete the course of nirmatrelvir/ritonavir, and none of the patients who received nirmatrelvir/ritonavir died of COVID-19 in the 30 days of follow-up.

CONCLUSIONS

A modified dose of nirmatrelvir/ritonavir use was found to be safe and well tolerated, with no serious adverse events being observed in a small sample of maintenance dialysis patients.

Serial SARS-CoV-2 antibody titers in vaccinated dialysis patients: prevalence of unrecognized infection and duration of seroresponse

Rationale & Objective

SARS-CoV-2 infections are likely underdiagnosed, but the degree of underdiagnosis among maintenance dialysis patients is unknown. Durability of the immune response after third vaccine doses in this population also remains uncertain. This study tracked antibody levels to 1) assess the rate of undiagnosed infections and 2) characterize seroresponse durability after third doses.

Study Design

Retrospective observational study.

Setting & Participants

SARS-CoV-2 vaccinated patients receiving maintenance dialysis through a national dialysis provider. Immunoglobulin G spike antibodies (anti-spike IgG) titers were assessed monthly following vaccination.

Exposures

Two and three doses of SARS-CoV-2 vaccine.

Outcomes

Undiagnosed and diagnosed SARS-CoV-2 infections; anti-spike IgG titers over time.

Analytical Approach

"Undiagnosed" SARS-CoV-2 infections were identified as an increase in anti-spike IgG titer of ≥ 100 BAU/mL, not associated with receipt of vaccine or "diagnosed" SARS-CoV-2 infection (by PCR or antigen test). In descriptive analyses, anti-spike IgG titers were followed over time.

Results

Among 2660 patients without prior COVID-19 who received an initial two-dose vaccine series, 371 (76%) SARS-CoV-2 infections were diagnosed and 115 (24%) were undiagnosed. Among 1717 patients without prior COVID-19 who received a third vaccine dose, 155 (80%) SARS-CoV-2 infections were diagnosed and 39 (20%) were undiagnosed. In both cohorts, anti-spike IgG levels declined over time. Of the initial two-dose cohort, 66% had a titer ≥ 500 BAU/mL in the first month, with 23% maintaining a titer ≥ 500 BAU/mL at six months. Of the third dose cohort, 95% had a titer ≥ 500 BAU/mL in the first month after the third dose, with 76% maintaining a titer ≥ 500 BAU/mL at six months.

Limitations

Assays used had upper limits.

Conclusions

Among maintenance dialysis patients, 20-24% of SARS-CoV-2 infections were undiagnosed. Given this population's vulnerability to COVID-19, ongoing infection control measures are needed. A three-dose primary mRNA vaccine series optimizes seroresponse rate and durability.

COVID-19 in Elderly Patients Receiving Haemodialysis: A Current Review

There is an increased incidence of elderly adults diagnosed with kidney failure as our global aging population continues to expand. Hence, the number of elderly adults indicated for kidney replacement therapy is also increasing simultaneously. Haemodialysis initiation is more commonly observed in comparison to kidney transplantation and peritoneal dialysis for the elderly. The onset of the coronavirus 2019 (COVID-19) pandemic brought new paradigms and insights for the care of this patient population. Elderly patients receiving haemodialysis have been identified as high-risk groups for poor COVID-19 outcomes. Age, immunosenescence, impaired response to COVID-19 vaccination, increased exposure to sources of COVID-19 infection and thrombotic risks during dialysis are key factors which demonstrated significant associations with COVID-19 incidence, severity and mortality for this patient group. Recent findings suggest that preventative measures such as regular screening and, if needed, isolation in COVID-19-positive cases, alongside the fulfillment of COVID-19 vaccination programs is an integral strategy to reduce the number of COVID-19 cases and consequential complications from COVID-19, particularly for high-risk groups such as elderly haemodialysis patients. The COVID-19 pandemic brought about the rapid development and repurposing of a number of medications to treat patients in the viral and inflammatory stages of their disease. However, elderly haemodialysis patients were grossly unrepresented in many of these trials. We review the evidence for contemporary treatments for COVID-19 in this population to provide clinicians with an up-to-date guide. We hope our article increases awareness on the associations and impact of COVID-19 for the elderly haemodialysis population, and encourage research efforts to address knowledge gaps in this topical area.

Lessons from SENCOVAC: A prospective study evaluating the response to SARS-CoV-2 vaccination in the CKD spectrum

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has negatively impacted on patients of the whole CKD spectrum, causing high rates of morbi-mortality. SARS-CoV-2 vaccines opened a new era, but patients with CKD (including kidney transplant, hemodialysis and peritoneal dialysis) were systematically excluded from pivotal clinical trials. The Spanish Society of Nephrology promoted the multicentric national SENCOVAC study aimed at assessing immunological responses after vaccination in patients with CKD. During the first year after vaccination, patients with non-dialysis CKD and those on hemodialysis and peritoneal dialysis presented good anti-Spike antibody responses to vaccination, especially after receiving the third and fourth doses. However, kidney transplant recipients presented suboptimal responses after any vaccination schedule (initial, third and fourth dose). Especially worrisome is the situation of a patients with a persistently negative humoral response that do not seroconvert after boosters. In this regard, monoclonal antibodies targeting SARS-CoV-2 have been approved for high-risk patients, although they may become obsolete as the viral genome evolves. The present report reviews the current status of SARS-CoV-2 vaccination in the CKD spectrum with emphasis on lessons learned from the SENCOVAC study. Predictors of humoral response, including vaccination schedules and types of vaccines, as well as the integration of vaccines, monoclonal antibodies and antiviral agents are discussed.

Immunogenicity of COVID-19 mRNA vaccines in hemodialysis patients: Systematic review and meta-analysis

Background and Aims

Vaccine response is a concern in hemodialysis patients. Given that hemodialysis patients were not included in clinical trials, we aimed to synthesize the available evidence on the immunogenicity of coronavirus disease 2019 (COVID-19) mRNA vaccines in hemodialysis patients.

Methods

We searched Scopus, PubMed, Sciencedirect, and finally google scholar databases for studies on COVID-19 mRNA-vaccines immunogenicity in hemodialysis patients up to December 1, 2021. Eligible articles measured antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike or Receptor-Binding Domain Antibody (S/RBD) postimmunization with COVID-19 mRNA vaccines. The immunogenicity of the vaccine was evaluated using seroconversion rates measured between 21 and 30 days after the first immunization and between 14 and 36 days post the second dose. We included studies including participants without a history of COVID-19 before vaccination. Healthy controls or health-care workers served as the control groups. After selecting eligible articles, the data were finally extracted from included articles. We used a random effects model to estimate the pooled seroconversion rate after COVID-19 mRNA vaccine administration. We assessed the heterogeneity between studies with the I 2 statistical index.

Result

We selected 39 eligible citations comprising 806 cases and 336 controls for the first dose and 6314 cases and 927 controls for the second dose for statistical analysis. After the first dose of mRNA vaccines, the seroconversion rate was 36% (95% confidence interval [CI]: 0.24-0.47) and 68% (95% CI: 0.45-0.91) in hemodialysis patients and the control group, respectively. While seroconversion rate after the second dose of mRNA vaccines was 86% (95% CI: 0.81-0.91) and 100% (95% CI: 1.00-1.00) in hemodialysis patients and the control group, respectively.

Conclusion

Although the immune response of hemodialysis patients to the second dose of the SARS-CoV-2 mRNA vaccine is very promising, the seroconversion rate of dialysis patients is lower than healthy controls. Periodically assessment of antibody levels of hemodialysis patients at short intervals is recommended.

SARS-CoV-2 spike protein antibody titers 6 months after SARS-CoV-2 mRNA vaccination among patients undergoing hemodialysis in Japan

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is shown to prevent severe illness and death in hemodialysis (HD) patients, but the immune response to vaccines is reduced in this population. This study compared SARS-CoV-2 spike protein antibody titers between HD patients and healthy controls in Japan for up to 6 months following vaccination.

METHODS

A multi-institutional retrospective study at five clinics in Japan was conducted using 412 HD patients and 156 healthy controls who received two doses of the BNT162b2 (Pfizer-BioNTech) mRNA vaccine. Anti-SARS-CoV-2 spike protein S1 IgG antibody titers were measured at 1, 3, and 6 months after the second dose. The attenuation speed was calculated as slope (i.e., -β) using a linear mixed-effects model toward the log-transformed antibody titers.

RESULTS

The HD group had significantly lower month 1 antibody titers (Ab-titer-1) than the controls, and these remained lower through month 6 (95% CI: 2617.1 (1296.7, 5240.8) vs. 7285.4 (4403.9, 11,000.0) AU/mL at Ab-titer-1, and 353.4 (178.4, 656.3) vs. 812.0 (498.3, 1342.7) AU/mL at Ab-titer-6 (p < 0.001, respectively)). Lower log Ab-titer-1 levels in the HD group were significantly associated with a lower log Ab-titer-6 (0.90 [0.83, 0.97], p < 0.001). The -β values in the HD patients and healthy controls were -4.7 ± 1.1 and -4.7 ± 1.4 (year-1), respectively.

CONCLUSION

SARS-CoV-2 spike protein antibody titers were significantly lower in HD patients than in healthy controls at 1 (peak) and 6 months after the second vaccination. Low peak antibody titers contributed to low 6-month antibody titers.

SARS-CoV-2 Infection during the Omicron Surge among Patients Receiving Dialysis: The Role of Circulating Receptor-Binding Domain Antibodies and Vaccine Doses

BACKGROUND

It is unclear whether circulating antibody levels conferred protection against SARS-CoV-2 infection among patients receiving dialysis during the Omicron-dominant period.

METHODS

We followed monthly semiquantitative SARS-CoV-2 RBD IgG index values in a randomly selected nationwide cohort of patients receiving dialysis and ascertained SARS-CoV-2 infection during the Omicron-dominant period of December 25, 2021 to January 31, 2022 using electronic health records. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status and by circulating RBD IgG using a log-binomial model accounting for age, sex, and prior COVID-19.

RESULTS

Among 3576 patients receiving dialysis, 901 (25%) received a third mRNA vaccine dose as of December 24, 2021. Early antibody responses to third doses were robust (median peak index IgG value at assay limit of 150). During the Omicron-dominant period, SARS-CoV-2 infection was documented in 340 (7%) patients. Risk for infection was higher among patients without vaccination and with one to two doses (RR, 2.1; 95% CI, 1.6 to 2.8, and RR, 1.3; 95% CI, 1.0 to 1.8 versus three doses, respectively). Irrespective of the number of vaccine doses, risk for infection was higher among patients with circulating RBD IgG <23 (506 BAU/ml) (RR range, 2.1 to 3.2, 95% CI, 1.3 to 3.4 and 95% CI, 2.2 to 4.5, respectively) compared with RBD IgG ≥23.

CONCLUSIONS

Among patients receiving dialysis, a third mRNA vaccine dose enhanced protection against SARS-CoV-2 infection during the Omicron-dominant period, but a low circulating RBD antibody response was associated with risk for infection independent of the number of vaccine doses. Measuring circulating antibody levels in this high-risk group could inform optimal timing of vaccination and other measures to reduce risk of SARS-CoV-2 infection.

SARS-CoV-2 Infections among Vaccinated Patients on Maintenance Dialysis, January 1-August 31, 2021, United States

Dialysis facilities voluntarily reported severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in vaccinated dialysis patients detected between January 1, 2021, and August 31, 2021, to the Centers for Disease Control and Prevention.Among 4087 patients reported, most were symptomatic, a third required hospitalization, and 9% died within 30 days of diagnosis.Monitoring SARS-CoV-2 infections and outcomes among vaccinated people on dialysis provides valuable insight into this population.

The Waxing, Waning, and Predictors of Humoral Responses to Vector-Based SARS-CoV-2 Vaccine in Hemodialysis Patients

Hemodialysis (HD) patients are vulnerable to coronavirus disease 2019 (COVID-19) and have a high mortality rate. We evaluated the anti-SARS-CoV-2 spike protein antibody (ACOV2S) levels in 385 HD patients before and 4 and 8 weeks after the second dose of vector-based ChAdOx1 nCoV-19 vaccine. For study control, week 4 ACOV2S levels after the second vaccination dose were measured in 66 healthcare workers (HCWs). The seroconversion rate of HD patients was 98.96% 4 weeks after the second vaccination. Despite low antibody levels before the second dose (week 0), week 4 ACOV2S levels after the second vaccine dose in HD patients increased prominently and were compatible with those in HCWs (p = 0.814 for HCWs vs. HD patients). The ACOV2S levels in HD patients waned significantly 8 weeks after the second vaccination dose (p < 0.001 at week 8 vs. 4). Older age and immunosuppressant use were negative predictors, while higher C-reactive protein (CRP) levels were positive predictors of ACOV2S waxing after the second vaccine dose in HD patients. Higher CRP levels and platelet counts were independently associated with decreased ACOV2S waning. The ChAdOx1 nCoV-19 vaccine is effective and safe for primary vaccination in HD patients and a booster dose is necessary.

Efficacy of SARS-CoV-2 Vaccination in Dialysis Patients: Epidemiological Analysis and Evaluation of the Clinical Progress

This study investigated the impact of the fourth COVID-19 pandemic wave on dialysis patients of Romagna territory, assessing the associations of vaccination status with infection risk, clinical severity and mortality. From November 2021 to February 2022, an epidemiological search was conducted on 829 patients under dialysis treatment for at least one month. The data were then analyzed with reference to the general population of the same area. A temporal comparison was also carried out with the previous pandemic waves (from March 2020 to October 2021). The epidemiological evolution over time in the dialysis population and in Romagna citizens replicated the global trend, as the peak of the fourth wave corresponded to the time of maximum diffusion of omicron variant (B.1.1.529). Of 771 prevalent dialysis patients at the beginning of the study, 109 (14.1%) contracted SARS-CoV-2 infection during the 4-month observation period. Vaccine adherence in the dialysis population of the reference area was above 95%. Compared to fully or partially vaccinated subjects, the unvaccinated ones showed a significantly higher proportion of infections (12.5% vs. 27.0% p = 0.0341), a more frequent need for hospitalization (22.2% vs. 50.0%) and a 3.3-fold increased mortality risk. These findings confirm the effectiveness of COVID-19 vaccines in keeping infectious risk under control and ameliorating clinical outcomes in immunocompromised patients.

COVID-19 and kidney disease: insights from epidemiology to inform clinical practice

Over the course of the COVID-19 pandemic, numerous studies have aimed to address the challenges faced by patients with kidney disease and their caregivers. These studies addressed areas of concern such as the high infection and mortality risk of patients on in-centre haemodialysis and transplant recipients. However, the ability to draw meaningful conclusions from these studies has in some instances been challenging, owing to barriers in aspects of usual care, data limitations and problematic methodological practices. In many settings, access to SARS-CoV-2 testing differed substantially between patient groups, whereas the incidence of SARS-CoV-2 infection varied over time and place because of differences in viral prevalence, targeted public health policies and vaccination rates. The absence of baseline kidney function data posed problems in the classification of chronic kidney disease and acute kidney injury in some studies, potentially compromising the generalizability of findings. Study findings also require attentive appraisal in terms of the effects of confounding, collider bias and chance. As this pandemic continues and in the future, the implementation of sustainable and integrated research infrastructure is needed in settings across the world to minimize infection transmission and both prevent and plan for the short-term and long-term complications of infectious diseases. Registries can support the real-world evaluation of vaccines and therapies in patients with advanced kidney disease while enabling monitoring of rare complications.

Immune responses to SARS-CoV-2 in dialysis and kidney transplantation

Despite progressive improvements in the management of patients with coronavirus disease 2019 (COVID-19), individuals with end-stage kidney disease (ESKD) are still at high risk of infection-related complications. Although the risk of infection in these patients is comparable to that of the general population, their lower rate of response to vaccination is a matter of concern. When prevention strategies fail, infection is often severe. Comorbidities affecting patients on maintenance dialysis and kidney transplant recipients clearly account for the increased risk of severe COVID-19, while the role of uremia and chronic immunosuppression is less clear. Immune monitoring studies have identified differences in the innate and adaptive immune response against the virus that could contribute to the increased disease severity. In particular, individuals on dialysis show signs of T cell exhaustion that may impair antiviral response. Similar to kidney transplant recipients, antibody production in these patients occurs, but with delayed kinetics compared with the general population, leaving them more exposed to viral expansion during the early phases of infection. Overall, unique features of the immune response during COVID-19 in individuals with ESKD may occur with severe comorbidities affecting these individuals in explaining their poor outcomes.

Anti-Spike antibodies three months after SARS-CoV-2 mRNA vaccine booster dose in patients on hemodialysis: the prospective SENCOVAC study

Introduction

Patients on hemodialysis are at high-risk for complications derived from coronavirus disease-19 (COVID-19). The present analysis evaluated the impact of a booster vaccine dose and breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on humoral immunity three months after the booster dose.

Methods

This is a multicentric and prospective study assessing IgG anti-Spike antibodies 6 and 9 months after initial SARS-CoV-2 vaccination in patients on hemodialysis that had also received a booster dose before the 6-month assessment (early booster) or between the 6- and 9-month assessments (late booster). The impact of breakthrough infections, type of vaccine, time from the booster and clinical variables were assessed.

Results

A total of 711 patients (67% male, 67 [20-89] years) were included. Of which, 545 (77%) received an early booster and the rest a late booster. At 6 months, 64 (9%) patients had negative anti-Spike antibody titers (3% of early booster and 29% of late booster patients, p = 0.001). At 9 months, 91% of patients with 6-month negative response had seroconverted and there were no differences in residual prevalence of negative humoral response between early and late booster patients (0.9% vs 0.6%, p = 0.693). During follow-up, 35 patients (5%) developed breakthrough SARS-CoV-2 infection. Antibody titers at 9 months were independently associated to mRNA-1273 booster (p = 0.001), lower time from booster (p = 0.043) and past breakthrough SARS-CoV-2 infection (p&lt;0.001).

Conclusions

In hemodialysis patients, higher titers of anti-Spike antibodies at 9 months were associated to mRNA-1273 booster, lower time from booster and past breakthrough SARS-CoV-2 infection.

BNT162b2 vaccine considerations for immunocompromised individuals: A global perspective

With the emergence of COVID-19 vaccines, individuals with comorbidities and immunosuppression require particular attention and should be prioritized for vaccination. However, the majority of vaccine clinical trials excluded people with comorbidities, resulting in a lack of data regarding vaccine efficacy in this demographic. Along with more inclusivity in clinical trials, reaching a definitive conclusion regarding vaccine efficacy in these patients is also crucial. In our review, we highlight the BNT162b2 vaccine safety and efficacy based on the limited number of clinical trials which included this demographic. We also provide vaccine considerations for individuals with cancer, autoimmune diseases, HIV, obesity, diabetes, organ transplant recipients and those undergoing maintenance haemodialysis to help them govern their decision regarding vaccine administration. In conclusion, further studies are required to alleviate any insecurities in patients with comorbidities regarding vaccination and it is recommended that patients are monitored post-vaccination to make sure sufficient immunity is achieved.

Adequacy of Hemodialysis Serves as an Independent Predictor of Humoral Response to ChAdOx1 Prime-Boost Vaccination in Hemodialysis Patients

Background: Immune response assessed by the quantification of neutralizing antibodies (nAbs) and predictors associated with immunogenicity after the prime-boost ChAdOx1 (Oxford−AstraZeneca) COVID-19 vaccine in hemodialysis (HD) patients remains unclear. Methods: This prospective study enrolled 174 HD patients and 67 healthy subjects to evaluate antibodies against the spike protein 1 and receptor-binding domain of severe acute respiratory syndrome coronavirus type 2 after prime-booster vaccination, by using enzyme-linked immunosorbent assay and applied spline-based generalized additive model regression analysis to predict 50% neutralization titer (NT50). The correlation between HD parameters and NT50 was analyzed. Results: NT50 was lower in HD patients compared with healthy controls after the prime-boost dose (p < 0.001). The geometric mean titer ratios were higher in first-dose seronegative than in the seropositive subgroup in HD patients and healthy controls (6.96 vs. 2.36, p = 0.002, and 9.28 vs. 1.26, p = 0.011, respectively). After two doses of ChAdOx1, one-way ANOVA showed that Ca × P was positively associated with NT50 (p trend = 0.043) and multiple linear regression showed the similar results (p = 0.021). Kt/V (a quantification of dialysis adequacy) (OR = 20.295, p = 0.005) could independently predict seroconversion (NT50 ≥ 35.13 IU/mL). Conclusion: Adequacy of hemodialysis could independently predict seroconversion in HD subjects vaccinated with prime-boost doses of ChAdOx1.

Diminished Short- and Long-Term Antibody Response after SARS-CoV-2 Vaccination in Hemodialysis Patients

Short-term studies have shown an attenuated immune response in hemodialysis patients after COVID-19-vaccination. The present study examines how antibody response is maintained after vaccination against SARS-CoV-2 in a large population of hemodialysis patients from six outpatient dialysis centers. We retrospectively assessed serum antibody levels against SARS-CoV-2 spike protein and nucleocapsid protein (electrochemiluminescence immunoassays, Roche Diagnostics) after COVID-19-vaccination in 298 hemodialysis and 103 non-dialysis patients (controls), comparing early and late antibody response. Compared to a non-dialysis cohort hemodialysis patients showed a favorable but profoundly lower early antibody response, which decreased substantially during follow-up measurement (median 6 months after vaccination). Significantly more hemodialysis patients had anti-SARS-CoV-2-S antibody titers below 100 U/mL (p < 0.001), which increased during follow-up from 23% to 45% but remained low in the control group (3% vs. 7%). In multivariate analysis, previous COVID-19 infections (p < 0.001) and female gender (p < 0.05) were significantly associated with higher early as well as late antibody vaccine response in hemodialysis patients, while there was a significant inverse correlation between patient age and systemic immunosuppression (p < 0.001). The early and late antibody responses were significantly higher in patients receiving vaccination after a SARS-CoV-2 infection compared to uninfected patients in both groups (p < 0.05). We also note that a higher titer after complete immunization positively affected late antibody response. The observation, that hemodialysis patients showed a significantly stronger decline of SARS-CoV-2 vaccination antibody titers within 6 months, compared to controls, supports the need for booster vaccinations to foster a stronger and more persistent antibody response.

SARS-CoV-2 infection during the Omicron surge among patients receiving dialysis: the role of circulating receptor-binding domain antibodies and vaccine doses

Background

It is unclear whether a third dose of mRNA platform vaccines, or antibody response to prior infection or vaccination confer protection from the Omicron variant among patients receiving dialysis.

Methods

Monthly since February 2021, we tested plasma from 4,697 patients receiving dialysis for antibodies to the receptor-binding domain (RBD) of SARS-CoV-2. We assessed semiquantitative median IgG index values over time among patients vaccinated with at least one dose of the two mRNA vaccines. We ascertained documented COVID-19 diagnoses after December 25, 2021 and up to January 31, 2022. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status using a log-binomial model accounting for age, sex, and prior clinical COVID-19. Among patients with RBD IgG index value available during December 1-December 24, 2021, we also evaluated the association between the circulating RBD IgG titer and risk for Omicron variant SARS-CoV-2 infection.

Results

Of the 4,697 patients we followed with monthly RBD assays, 3576 are included in the main analysis cohort; among these, 852 (24%) were unvaccinated. Antibody response to third doses was robust (median peak index IgG value at assay limit of 150, equivalent to 3270 binding antibody units/mL). Between December 25-January 31, 2022, SARS-CoV-2 infection was documented 340 patients (7%), 115 (36%) of whom were hospitalized. The final doses of vaccines were given a median of 272 (25 th , 75 th percentile, 245-303) days and 58 (25 th , 75 th percentile, 51-95) days prior to infection for the 1-2 dose and 3 dose vaccine groups respectively. Relative risks for infection were higher among patients without vaccination (RR 2.1 [95%CI 1.6, 2.8]), and patients with 1-2 doses (RR 1.3 [95%CI 1.0, 1.8]), compared with patients with three doses of the mRNA vaccines. Relative risks for infection were higher among patients with RBD index values < 23 (506 BAU/mL), compared with RBD index value ≥ 23 (RR 2.4 [95%CI 1.9, 3.0]). The higher risk for infection among patients with RBD index values < 23 was present among patients who received three doses (RR 2.1 [95%CI 1.3, 3.4]).

Conclusions

Among patients receiving hemodialysis, patients unvaccinated, without a third mRNA vaccine dose, or those lacking robust circulating antibody response are at higher risk for Omicron variant infection. Low circulating antibodies could identify the subgroup needing intensified surveillance, prophylaxis or treatment in this patient population.