Immune responses to COVID-19 mRNA vaccination appear strong in patients on hemodialysis, but less certain in kidney transplant recipients, in whom these responses may vary by immunosuppressive regimen, according to a new study.
Based on a study of patients who received the Pfizer-BioNTech COVID-19 mRNA (BNT162b) vaccine, investigators concluded that vaccination should be highly recommended in patients on hemodialysis awaiting a transplant, but the current vaccine strategy for kidney transplant recipients “may not provide effective protection against COVID-19 and will likely need to be improved.”
Dominique Bertrand, MD, of Rouen University Hospital in Rouen, France, and colleagues studied the first 45 kidney transplant recipients (mean age 63.5 years) and 10 patients on hemodialysis (mean age 71.2 years) in a cohort to receive 2 injections of the Pfizer-BioNTech COVID-19 mRNA (BNT162b2) vaccine.
At 1 month after the second dose, anti-spike SARS-CoV-2 antibodies developed in 8 patients on hemodialysis (88.9%) and 8 kidney transplant recipients (17.8%), the investigators reported. The median antibody titer in responders was 1052 AU/mL in patients on dialysis and 671 AU/mL in kidney transplant recipients.
After the second vaccine dose, a specific T cell response was detected in 9 patients (90%) on hemodialysis (1 patient contracted COVID-19 and was excluded) and 26 (57.8%) kidney transplant recipients. In responders, the median number of spike-reactive T cells were 305 spot-forming cells (SFC) per 106 CD3+ T cells in patients on hemodialysis and 212 SFC/106 CD3+ T cells in kidney transplant recipients.
The immune response in kidney transplant recipients appeared to vary by immunosuppressive regimen. Patients receiving belatacept had no antibody response and no or few specific T cells, Dr Bertrand’s team reported. Tacrolimus-treated patients generally had a weak response, except for a few patients who mounted a T cell response. Most of the kidney transplant group received mycophenolate mofetil, which may have influenced antibody responses.
According to Dr Bertrand’s team, the Pfizer-BioNTech COVID-19 mRNA vaccine “seems efficient” in patients on hemodialysis, supporting vaccination of these patients. By contrast, the low seroconversion rate observed in kidney transplant recipients is “worrying.”
Commenting on the new study in an interview with Renal & Urology News, Liise-anne Pirofski, MD, chief of the Division of Infectious Diseases at Albert Einstein College of Medicine and Montefiore Medical Center in the Bronx, New York, said the latest findings provide some confidence that patients on hemodialysis may be protected by vaccination. Dr Pirofski pointed out, however, that patients who remain on dialysis because they are not transplant candidates may not have responses as robust as individuals who are candidates. Baseline immunologic function is important.
“Nonetheless, that certain kidney transplant recipients and patients on hemodialysis generate T-cell responses suggest these high-risk groups may be able to mount a response to the virus or vaccination, with the caveat that the ability of kidney transplant recipients to respond is influenced by their immunosuppressive regimen,” Dr Pirofski said. “More data, including real-world data on vaccine effectiveness, are needed to fully characterize the responses of kidney transplant recipients and patients on hemodialysis in relationship to each other and healthy individuals.”
In their study discussion, Dr Bertrand and colleagues pondered what might be an effective strategy for vaccinating kidney transplant recipients. Dr Pirofski offered some insight.
Studies to address the effect of mixed platform vaccinations — for example giving mRNA after vectored vaccines and vice versa — are ongoing, Dr Pirofski said. “Ample data now show that people who have recovered from COVID-19 generate very robust SARS-CoV-2 vaccine responses. Thus, it is reasonable to posit that additional vaccine doses will expand exposure of the immune system to spike protein antigens potentially boosting minimal or inducing de novo antibody and/or T cell responses. Different vaccine platforms may induce a broader, more robust response and/or stimulate responses via diverse immunologic pathways. This is the idea behind prime-boost protocols.”
The outstanding question is whether people who did not generate an antibody response after their first vaccine will do so after receiving a different vaccine, she said.
“The best way to protect vaccine non-responders now is to protect them from infection by vaccinating people around them,” Dr Pirofski said. “They and their contacts should continue to wear masks, especially in areas where viral variants such as the Delta variant are circulating. The health care community should consider the use of monthly SARS-CoV-2 monoclonal antibody prophylaxis.”
Disclosure: Some study author(s) declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Bertrand D, Hamzaoui M, Lemée V, et al. Antibody and T cell response to SARS-CoV-2 messenger RNA BNT162b2 vaccine in kidney transplant recipients and hemodialysis patients. J Am Soc Nephrol. Published online June 9, 2021. doi:10.1681/ASN.2021040480