Study reveals how patients on hemodialysis respond to Pfizer’s COVID-19 vaccine
Research in Israel showed that while patients on maintenance hemodialysis had a “substantial” antibody response to the COVID-19 vaccine from Pfizer and BioNTech, the response was lower than that seen for those without kidney disease.
Age also appeared to play an important role for all participants’ humoral immune response, results suggested.
“Prioritizing patients on dialysis for vaccination has been at the forefront of SARS-CoV-2 vaccination programs internationally,” Ayelet Grupper, MD, of Tel Aviv Medical Center, and colleagues, wrote. “Patients with CKD, but especially those with kidney failure, treated with maintenance [hemodialysis] HD tend to have a reduced immune response to infection or vaccination, as demonstrated with the hepatitis B virus vaccine. Consequently, there is often a need for higher vaccine dosage or scheduling changes in these patients.
This study is aimed at establishing one aspect of the immune response, the humoral response to the BNT162b2 (PfizerBioNTech) vaccine in patients with kidney failure on maintenance HD.”
Researchers compared the response of 56 patients on dialysis to that of 95 health care workers (serving as controls) at a median of 30 days after receiving the second dose of the vaccine.
All participants in the control group developed an antibody response vs. 96% of patients on dialysis.
Specific observations related to differences in response between the groups showed immunoglobulin G levels were significantly lower for patients in the dialysis group compared with controls (median of 2,900 vs. 7,401), and the odds of being in the lower quartile of IgG levels were 2.7 times higher for patients on dialysis.
Within the dialysis group, those who were older or who also had lower lymphocyte count were most likely to have lower IgG levels (OR of 1.22 per 1-year older and 0.83 per 10-e3/mL-higher lymphocyte count).
Age was significant for both groups, with the odds of being in the lower IgG quartile found to be 1.11 times higher per year of age.
According to Gupper and colleagues, this finding (which more specifically showed little difference in antibody response for participants older than 70 years) suggests age is an important factor regardless of medical conditions.
Researchers also pointed out some limitations of the study, noting their study population did not allow for consideration of the potential role race and ethnicity might play.
“In many countries, incidence and/or severity of COVID-19 have varied by ethnicity, which we could not investigate due to the homogenous nature of our maintenance HD population,” they wrote.
In addition, they indicated the “considerable age difference” between patients on dialysis and the health care workers is important to keep in mind, as the former had a mean age of 74 years compared with 57 years.
Despite the limitations, the researchers highlighted how the study contributes to the understanding of vaccine impact for this patient population.
“Although the level of the humoral response in most patients on maintenance HD in our study is considered positive, the weaker seroresponse (relative to controls and the populations in which the vaccine trials were conducted) may have consequences, including lower vaccine efficacy to the parent strain or to variants that are evolving and/or a shorter period of immunoprotection after vaccination,” they wrote.
In a related press release, co-investigator Moshe Shashar, MD, shared his perspective on how the results may be useful going forward.
“I believe our findings should encourage patients with kidney failure treated with dialysis to be vaccinated as soon as vaccination becomes available for them, while we as care givers should explore ways to enhance its efficacy in our patients,” he said.