Patients with chronic kidney disease, including those on dialysis, have been prioritized for vaccination due to increased risk of severe COVID-19 outcomes such as hospitalization and death. In a CITF-funded study now published in JAMA Network Open, several CITF and VSRG-affiliated researchers, including Drs. Michelle Hladunewich and Matthew Oliver report that many dialysis patients have weak antibody responses after the first dose of the Pfizer-BioNTech vaccine; a second dose however induces a more robust response, suggesting that the second dose should not be delayed in these at-risk individuals. The study also found the Pfizer vaccine to be safe among all participant groups.

A new study led by COVID-19 Immunity Task Force (CITF) and Vaccine Surveillance Research Group (VSRG)-funded researchers Drs. Michelle Hladunewich and Matthew Oliver from Sunnybrook Health Sciences Centre, in collaboration with CITF-affiliated researchers Drs. Anne-Claude Gingras, Karen Colwill and Allison McGeer from Sinai Health System, Dr. Sharon Straus from Unity Health Toronto, and Drs. Shelly Bolotin and Vanessa Tran from Public Health Ontario and the VSRG, looked at the antibody responses of patients with chronic kidney disease undergoing dialysis. Patients were recruited from the Sunnybrook Health Sciences Centre in Toronto between February 2 and March 3, 2021 (n=142). A total of 35 healthcare workers were also recruited as healthy controls.

Key Points:

  • Many dialysis patients were observed to have weak antibody responses after the first dose of the Pfizer vaccine compared to healthcare worker controls and plasma from COVID-19-recovered individuals. A second dose, however, induced a more robust response.
  • The authors highlighted the need for dialysis patients to receive the second dose according to the manufacturer’s recommended two-dose schedule for optimal protection.
  • Some dialysis patients fail to mount a strong response to two-doses, indicating that careful and ongoing monitoring of this patient population is imperative, particularly in light of the potential need for third (‘booster’) doses.

Researchers compared the SARS-CoV-2 antibody levels in dialysis patients taken from two groups. The first group had blood samples taken 28 days after receiving the first dose of the Pfizer vaccine. The second group had samples taken prior to and 14 days after the second dose of the Pfizer vaccine. The results indicated that more patients developed SARS-CoV-2 antibodies to the spike protein (69/72; 96%) and receptor-binding domain (RBD) protein (63/72; 88%) after receiving two doses compared to those who had received only one dose (53/66 (80%) for spike and 36/66 (55%) for RBD). Additional analysis indicated that after two doses, more participants had comparable SARS-CoV-2 antibody levels to patients who had recovered from a SARS-CoV-2 infection (72% for spike and 60% for RBD) than patients administered with only one dose (23% for spike and 6% for RBD). All healthcare workers in the control group produced high levels of SARS-CoV-2 spike and RBD antibodies following two doses, which exceeded the levels found in plasma from COVID-19-recovered individuals. The researchers also evaluated vaccine safety, which indicated that the vaccine was safe and well-tolerated after both the first and second dose among all participants.

This study highlights a reduced antibody response among dialysis patients 28 days following a single dose of the Pfizer vaccine. This has also been observed by other groups in other immunocompromised populations, including patients with blood cancers and solid organ transplant recipients. Altogether, the authors demonstrated that many dialysis patients remain at risk for SARS-CoV-2 infection following the first dose of a vaccine and advocate for the adherence to the manufacturer’s recommended dosing schedule for more rapid protection. They also note that in contrast to healthy individuals, some dialysis patients fail to mount a strong response to the two-dose vaccination regimen, indicating that careful and ongoing monitoring of this patient population is imperative, particularly in light of the potential need for third (‘booster’) doses.

This study first appeared online as a preprint on medRxiv. It is now published in JAMA Network Open Nephrology.

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Yau K, Abe KT, Naimark D, Oliver MJ, Perl J, Leis JA, Bolotin S, Tran V, Mullin S, Shadowitz E, Garnham-Takaoka J, de Launay KQ, Takaoka A, Straus SE, McGeer AJ, Chan CT, Colwill K, Gingras A-C, Hladunewich MA. Evaluation of the SARS-CoV-2 Antibody Response to the BNT162b2 Vaccine in Patients Undergoing Hemodialysis. JAMA Netw Open 2021 Sep 1. doi:10.1001/jamanetworkopen.2021.23622.