A Malaysian Study on COVID-19 (SARS-CoV-2) Vaccination Immune Response in Haemodialysis patients: A prospective, multicenter, cohort study

doi:10.21203/rs.3.rs-5308635/v1

Background: Patients with end-stage renal disease (ESRD) have compromised immune systems, possibly reducing their vaccine-induced antibody responses compared to the general population. This study aims to determine the immunogenicity of this group to the COVID-19 vaccine.

Methods: Haemodialysis patients receiving the Pfizer-BioNTech mRNA vaccine were followed for at least 13 months. Blood samples were collected prior to every vaccine dose and at multiple intervals thereafter. Neutralising antibodies (nAb) against SARS-CoV-2 were measured. Patients voluntarily reported any COVID-19 infection.

Results: Between April 2021 and January 2023, 271 patients received at least one dose of the vaccine; 212 of these had at least one blood sample tested for nAb. Booster doses were given 26.2 weeks after the second dose. nAbs were detected in 16.8% of patients before vaccination. The nAb levels were higher than the non-convalescent patients after the first dose, but it was not statistically significant. Breakthrough infections occurred in 29.3% patients. They were not associated with history of COVID-19 infection (p=0.188). There were 34 deaths (16.0%); 2 related to COVID-19. Younger age was associated with higher nAb reactivity post-first dose, but this difference diminished after the second dose.

Conclusion: Almost complete seropositivity (98.4%) was achieved after two doses of vaccine. Sustained antibody levels after the third dose underscore the importance of a booster dose in protecting this vulnerable population. However, the occurrence of breakthrough infections highlights the need for continued monitoring, preventive measures, and further research to optimize vaccination strategies in haemodialysis patients.

Infectious Diseases

COVID-19 vaccine

haemodialysis

end-stage renal disease (ESRD)

As of 2024, the WHO has reported over 700 million COVID-19 cases globally. In Malaysia, there have been more than 5 million cases, resulting in over 30,000 deaths [1]. The rise in hospitalizations and mortality has added a significant burden to the healthcare system. In the latest report, more than 50000 individuals with end stage renal disease (ESRD) in Malaysia were on dialysis in 2022 [2]. The COVID-19 pandemic has significantly impacted this population, who are at a higher risk of infection compared to healthy individuals due to their compromised immune systems.

The lack of vitamin D and erythropoietin and accumulation of uremic toxins in ESRD patients affects the immune function of these patients. On top of that, the main receptor of SARS-CoV-2, the angiotensin converting enzyme 2 (ACE 2), is highly expressed in the kidney. All these conditions can induce cytokine storms, inflammation and oxidative stress, and in return, further damaging the kidney and worsening the severity of the infection [3]. The overall estimated case fatality rate of COVID-19 in ESRD patients undergoing renal replacement therapy was 18.06%, significantly higher than the global average of 4.98% [4].

Vaccine development began in 2020 with the goal of preventing and reducing the morbidity and mortality caused by COVID-19. In December 2020, the FDA granted the first Emergency Use Authorization (EUA) for a vaccine designed to prevent COVID-19 [5]. Currently, there are two mRNA vaccines that encode the SARS-CoV-2 spike protein—Pfizer-BioNTech and Moderna. In Malaysia, haemodialysis patients received the Pfizer-BioNTech vaccine. Research indicates that two doses of the Pfizer-BioNTech vaccine are 94-95% effective in preventing confirmed COVID-19 cases and 75% effective in preventing severe COVID-19 in the general population [6,7].

However, the effectiveness of the vaccine can differ based on various factors such as age, comorbidities, and immune status. In ESRD patients, the efficacy of the vaccine further depends on factors such as lack of vitamin D and erythropoietin, uremic conditions and use of immunosuppressants [3]. Seroconversion rates and antibody titers have been found to be significantly lower in ESRD patients, whether on dialysis or not, compared with healthy individuals [8–11]. Nevertheless, in haemodialysis patients, one dose of vaccine can reduce the risk of infection and serious outcomes by 41% and 46%, respectively, while two doses can bring these numbers to 69% and 83% [3].

The Centers for Disease Control and Prevention (CDC) recommends that individuals who are severely or moderately immunocompromised should receive two or three doses of the same brand of COVID-19 vaccine [12]. They may also be eligible for additional doses. The use of additional doses is to enhance immunity, extend the duration of protection, and improve their ability to produce sufficient immune responses. No specific COVID-19 vaccine is preferred over another.

This study was carried out after the COVID-19 vaccine became available in Malaysia in early 2021, with the aim to gather local data examining the immune response of mRNA COVID-19 vaccine in haemodialysis patients and hence, to guide our national COVID-19 vaccination plan for this specific population. We find that there is still a lack of evidence on the immunogenicity and breakthrough infections representing the Malaysian population. This study provides real-world data on the effectiveness of the Pfizer-BioNTech (BNT162b2) COVID-19 vaccine in haemodialysis patients from this region.

This study was conducted in eight dialysis units across four states in Peninsula Malaysia. Patients on haemodialysis who participated in COVID-19 vaccination program were eligible to be enrolled in this study and were prospectively followed up for at least 13 months. All subjects received the Pfizer-BioNTech (BNT162b2) mRNA vaccine. Full COVID-19 vaccination was defined as two doses of the vaccine administered 3 weeks apart. Booster dose was optional and was administered at least six months after the second dose.

All blood samples (3 - 5 ml) were taken by trained healthcare personnel at each center. Baseline blood sample was taken on the day before the first vaccination dose. Subsequent blood samples were taken again before the second dose and one, six and 12 months thereafter (Figure 1). Additional sampling points were drawn for those who took three doses of the vaccine. These blood samples were then sent to the laboratory to be spun at 1000 x G for 15 minutes in a refrigerated centrifuge at 20˚C and the sera aliquoted into cryotubes. The cryotubes were then stored in a -80 ˚C freezer before being sent to the Institute of Medical Research to be analyzed.

All samples were tested for IgG antibody against SARS-CoV-2 spike protein (S1) receptor-binding domain (RBD) by trained personnel, using the ADVIA Centaur SARS-CoV-2 spike IgG assay, sCOVG (Siemens Healthcare Diagnostic, NY, USA). The sCOVG assay is a fully automated two-step sandwich immunoassay using indirect chemiluminescent technology for qualitative and quantitative detection of IgG, including neutralising antibodies (nAb). The assay outputs an sCOVG index value was standardised to the WHO International Standard for anti-SARS-CoV-2 Immunoglobulin unit BAU/ml using a conversion factor of 21.8 [13]. The positive threshold was 21.8 BAU/ml.

COVID-19 status was voluntarily reported by the patients. Breakthrough infection was defined as a SARS-CoV-2 virus infection that occurred at least 14 days after the last COVID-19 vaccine dose.

Statistical analysis

Continuous variables were summarized as means and standard deviations while categorical variables were expressed as frequencies and percentages. Chi-squared test or Fisher’s exact test was used to compare between groups. Analysis was performed using STATA 11. A p-value of <0.05 was considered statistically significant.

Between April 2021 and January 2023, 271 patients (52.0% males) with a mean (SD) age of 61.1 (14.4) years received at least one dose of the Pfizer-BioNTech (BNT162b2) mRNA vaccine.

Of these, 212 patients who had at least one blood sample tested for neutralising antibodies were included in the study. Characteristics of these patients are shown in Table 1. Booster dose was administered on average 26.2 weeks after the second dose. Median interval time between the second and booster doses was 25.4 weeks. There were 34 deaths (16.0%), of which two were related to COVID-19.

Breakthrough infections occurred in 62 (29.3%) patients; 21 (33.9%) and 41 (66.1%) occurred after the second and third doses, respectively, with a median time of 14.3 weeks after the second dose and 16.6 weeks after the third. Overall, a median (IQR) time of 15.5 (13.7, 18.1) weeks elapsed between the last vaccination dose and breakthrough infection. Seven (11.3%) of these patients were convalescent patients. There was no association between history of COVID-19 infection and breakthrough infection (p=0.188).

Table 1. Characteristics of subjects, n = 212

Characteristics
Mean age, years (SD)	59.7 (14.7)
Gender
Male, n (%)	112 (52.8)
Female, n (%)	100 (47.2)
Ethnicity
Malay, n (%)	99 (46.7)
Chinese, n (%)	90 (42.5)
Indian, n (%)	15 (7.1)
Others, n (%)	8 (3.8)
Total doses of COVID-19 vaccine received
2 doses, n (%)	25 (11.8)
2 doses + booster, n (%)	187 (88.2)

Neutralising antibody response

At some timepoints, the number of samples may be less than the total number of patients as some samples were compromised, volume was too little, or sample was not taken. The number of samples analyzed are stated in the denominator.

Neutralising antibodies against SARS-CoV-2 were detected in 16.8% (n=35/208) ESRD patients at baseline before their first vaccination dose, likely an indication of a recent or prior COVID-19 infection. The median (IQR) nAb titre among these convalescent individuals at baseline were 32.7 BAU/ml (24.6, 72.4) and ranged between 16.1 and 2180 BAU/ml, which was the upper limit of detection.

Neutralising antibodies were detected in 61.9% (n=130/210, median: 95.8 BAU/ml) and 98.4% (n=185/188, median: 2180 BAU/ml) patients after the first and second doses, respectively. The median nAb titres were higher three weeks after the first dose in patients previously exposed to COVID-19 infection (71.6 vs 35.1 BAU/ml) (Figure 2). However, it was not statistically significant (p=0.09). There were also no statistically significant differences in the neutralising antibody reactivity post-first and second doses between convalescent and non-convalescent individuals (Table 2).

Table 2. Neutralising antibody reactivity after doses 1 and 2

	Prior COVID-19 infection		p-value²
	No	Yes
3 weeks post Dose 1
Non-reactive	70 (39.8%)	10 (29.4%)	0.255
Reactive¹	106 (60.2%)	24 (70.6%)
1 month post Dose 2
Non-reactive	1 (0.7%)	2 (6.1%)	0.08
Reactive¹	154 (99.4%)	31 (93.9%)

¹ Reactive (or positive) is determined according to the neutralising antibody index value of ≥ 1.00 U/ml (21.8 BAU/ml)

² Chi-squared test or Fisher’s Exact test

Median nAb titres reached its peak detectable limit for all vaccinated patients 1 month (mean 4.4 weeks) after the second dose. The median level was reduced to 174.5 BAU/ml by the sixth month (mean 23.5 weeks). However, after the third dose, median nAb levels remained consistently high until the last observed sample 12 months later.

We found younger age to be significantly associated with nAb reactivity at 3 weeks post-first dose (adjusted OR 0.96, 95% CI 0.92, 0.97, p<0.001). The differences were no longer significant after the second dose.

Patients with ESRD have compromised immune systems and comorbidities thus they are at a higher risk of severe COVID-19, and possibly reduced vaccine-induced antibody responses compared to the general population [14,15].

We observed an almost complete seropositivity rate (98.4%) in our samples after two doses of the Pfizer- BNT162b2 vaccine compared to just one dose. Additionally, we found that patients with prior SARS-CoV-2 exposure had higher median nAb titers after the first dose of the vaccine, although this difference was not statistically significant. This finding is consistent with a study examining antibody responses after multiple doses of the same vaccine [16], reinforcing the understanding that prior infection can prime the immune system, but vaccination provides a significant boost in antibody levels regardless of prior exposure. With two doses, the antibody titer levels in all patients reached the maximum detectable limit, further justifying the importance of completing the full vaccination course.

We also observed a waning in median nAb titers six months after the second dose, nevertheless levels were amplified and remained consistently high after the third (booster) dose. This supports the rationale behind booster dose recommendations, particularly for vulnerable populations, as emphasized by the "Coronavirus Disease 2019 (COVID-19)" (2023) [17]. Our findings provide real-world evidence supporting this vaccination strategy in haemodialysis patients.

The occurrence of breakthrough infections is consistent with the understanding that while vaccination significantly reduces the risk, it does not completely eliminate the possibility of an infection. Breakthrough infection occurred in 29.3% of our patients, which was quite high compared to other studies in haemodialysis patients [18,19]. This is possibly due to the study periods and new variants that are either more contagious or more deadly. Most of the breakthrough infections in our study coincided with the period when the highly infective Omicron variant was widespread, possibly explaining the high rate of infections [20]. However, there were no serious complications except in two cases where the patients died.

In our cohort, more patients were positive after three doses compared to two. This could possibly be explained by changes in attitude and practice, that could lead to higher chances of contracting the disease.

Our study has a few weaknesses. Firstly, breakthrough infection status was based on self-report. Thus, there may be an underreport, especially if they were asymptomatic. Secondly, blood-taking was done at fixed intervals, therefore we were unable to correlate with the antibody titers before and after a breakthrough infection. Lastly, we did not have data to do a comparison of antibody titers with non-dialysed patients.

Our results contribute to the growing body of evidence supporting the immunogenicity of this vaccine in haemodialysis patients. The high seropositivity rates and the sustained antibody levels after the booster dose underscore the importance of this vaccine in protecting this vulnerable population.

However, the occurrence of breakthrough infections highlights the need for continued monitoring, preventive measures, and further research to optimize vaccination strategies in haemodialysis patients.

ACKNOWLEDGEMENT

We would like to thank the Director General of Health Malaysia for his permission to publish this article, and the Malaysian Ministry of Health for the Research Grant (MRG) that made this study a success.

We would like to acknowledge Nur Farhain Muhamad Bustaman, Nurhannah Nabyllah binti Ramizan, Ahmad Hafiz Murtadha and Ahmad Zharif bin Ismail from Primer Immunodeficiency Unit, Allergy and Immunology Research Center, IMR, NIH for running the lab tests.

We would also like to thank the following personnels for managing patients’ recruitment, handling and processing blood samples, gathering reports on COVID-19 infection status, and entering data, which made this multicentred study a success. Namely:

Iqbal Haniff bin Mohd Fadzil and Noor Kamila Abdullah from Hospital Sultanah Bahiyah. Ooi Lee Choo from TzuChi Dialysis Center, and Wei Kim Lan from Albukhary Dialysis Center of Kedah.
Dr Norleen Zulkarnain Sim, Che Ku Yusran Bin Che Ku Hasan, and Dr Irene Wong from Department of Nephrology, as well as the Chemical Pathology Unit Staff, of Hospital Tengku Ampuan Rahimah, Selangor.
Dr Mohd Yusran bin Yusoff from CRC, Dr Azura Hussin and staff of Molecular Lab, Hospital Raja Perempuan Zainab II. Ab Farid Fajilah Bin Ab Aziz from Al-musoffa Dialysis Center, Mohd Rafidi Bin Ab Rauf from Haemodialysis Unit of Hospital Tengku Anis, and Azartini Yusof from Darul Naim Dialysis Center of Kelantan.
Mohd Sufian Bin Sulaiman from Haemodialysis Unit of Hospital Pulau Pinang, Wong Loy Sin from National Kidney Foundation Fo-Yi Unit-2 Dialysis Center. Dr Tan RuiXin, Angelyn Ann Yeoh, Nurul Aimi Bt Mohd Ariffin, and Noraznizah Binti Brahim from Pathology lab of Hospital Pulau Pinang, Penang.

ETHICAL DISCLOSURES

Each patient gave informed consent to participate in this study and to have their blood samples taken for analysis. This study was approved by the Medical Research and Ethics Committee of Malaysia.

Health M of. COVID-19 · Malaysia | KKMNOW [Internet]. [cited 2024 Sep 24]. Available from: https://data.moh.gov.my
30th Report of the Malaysian Dialysis and Transplant Registry 2022 – NRR – National Renal Registry [Internet]. [cited 2024 Sep 24]. Available from: https://www.msn.org.my/nrr/30th-report-of-the-malaysian-dialysis-and-transplant-registry-2022/
Zhang X, Chen Q, Xu G. Clinical manifestations of COVID-19 infection in dialysis patients and protective effect of COVID-19 vaccine. Inflamm Res Off J Eur Histamine Res Soc Al. 2023 May;72(5):989–1000.
Nopsopon T, Kittrakulrat J, Takkavatakarn K, Eiamsitrakoon T, Kanjanabuch T, Pongpirul K. COVID-19 in end-stage renal disease patients with renal replacement therapies: A systematic review and meta-analysis. PLoS Negl Trop Dis. 2021 Jun;15(6):e0009156.
Commissioner O of the. FDA. FDA; 2020 [cited 2024 Sep 24]. FDA Takes Key Action in Fight Against COVID-19 By Issuing Emergency Use Authorization for First COVID-19 Vaccine. Available from: https://www.fda.gov/news-events/press-announcements/fda-takes-key-action-fight-against-COVID-19-issuing-emergency-use-authorization-first-COVID-19
Polack FP, Thomas SJ, Kitchin N, Absalon J, Gurtman A, Lockhart S, et al. Safety and Efficacy of the BNT162b2 mRNA COVID-19 Vaccine. N Engl J Med. 2020 Dec 31;383(27):2603–15.
Dagan N, Barda N, Kepten E, Miron O, Perchik S, Katz MA, et al. BNT162b2 mRNA COVID-19 Vaccine in a Nationwide Mass Vaccination Setting. N Engl J Med. 2021 Apr 15;384(15):1412–23.
Schrezenmeier E, Bergfeld L, Hillus D, Lippert JD, Weber U, Tober-Lau P, et al. Immunogenicity of COVID-19 Tozinameran Vaccination in Patients on Chronic Dialysis. Front Immunol. 2021;12:690698.
Kanai D, Wakui H, Haze T, Azushima K, Kinguchi S, Tsukamoto S, et al. SARS-CoV-2 spike protein antibody titers 6 months after SARS-CoV-2 mRNA vaccination among patients undergoing hemodialysis in Japan. Clin Exp Nephrol. 2022 Oct;26(10):988–96.
Grupper A, Sharon N, Finn T, Cohen R, Israel M, Agbaria A, et al. Humoral Response to the Pfizer BNT162b2 Vaccine in Patients Undergoing Maintenance Hemodialysis. Clin J Am Soc Nephrol CJASN. 2021 Jul;16(7):1037–42.
Zhao T, Nishi-Uchi T, Omata F, Takita M, Kawashima M, Nishikawa Y, et al. Humoral response to SARS-CoV-2 vaccination in haemodialysis patients and a matched cohort. BMJ Open. 2022 Nov 8;12(11):e065741.
CDC. COVID-19. 2024 [cited 2024 Sep 24]. Vaccines for Moderately to Severely Immunocompromised People. Available from: https://www.cdc.gov/COVID/vaccines/immunocompromised-people.html
Understanding SARS-CoV-2 IgG Immunity Thresholds and the Process of Standardization [Internet]. [cited 2024 Sep 30]. Available from: https://www.siemens-healthineers.com/en-id/laboratory-diagnostics/assays-by-diseases-conditions/infectious-disease-assays/sars-cov-2-assay-clinical-performance/whitepaper-understanding-sars-cov-2-igg-immunity-thresholds
Sia IG, Paya CV. Infectious complications following renal transplantation. Surg Clin North Am. 1998 Feb;78(1):95–112.
Miura M, Fukumoto M, Komatsu N, Shuto R, Harada H, Sasaki H. Temporary reduction of immunosuppression enhances production of anti-S antibody against severe acute respiratory syndrome coronavirus 2 after vaccination in kidney transplant recipients. Int J Urol Off J Jpn Urol Assoc. 2022 Dec;29(12):1505–10.
Sheehan J, Ardizzone CM, Khanna M, Trauth AJ, Hagensee ME, Ramsay AJ. Dynamics of Serum-Neutralizing Antibody Responses in Vaccinees through Multiple Doses of the BNT162b2 Vaccine. Vaccines. 2023 Nov;11(11):1720.
Coronavirus Disease 2019 (COVID-19): Practice Essentials, Background, Route of Transmission. 2024 May 1 [cited 2024 Aug 15]; Available from: https://emedicine.medscape.com/article/2500114-overview?form=fpf
Smits PD, Gratzl S, Simonov M, Nachimuthu SK, Goodwin Cartwright BM, Wang MD, et al. Risk of COVID-19 breakthrough infection and hospitalization in individuals with comorbidities. Vaccine. 2023 Apr 6;41(15):2447–55.
Patnaik AP, Rout NK, Ahmed S, Dash KA, Praharaj AK, Patro ARK. Correlation of Breakthrough Infection During the Omicron Wave With Seropositivity of Vaccinated Patients Undergoing Hemodialysis. Cureus. 2022 Sep;14(9):e29296.
El Karoui K, De Vriese AS. COVID-19 in dialysis: clinical impact, immune response, prevention, and treatment. Kidney Int. 2022 May;101(5):883–94.

The authors declare no competing interests.

A Malaysian Study on COVID-19 (SARS-CoV-2) Vaccination Immune Response in Haemodialysis patients: A prospective, multicenter, cohort study

Status:

Version 1

Abstract

Figures

INTRODUCTION

METHODOLOGY

RESULTS

DISCUSSION

CONCLUSION

Declarations

REFERENCES

Additional Declarations

Status:

Version 1