This is a summary, written by members of the CITF Secretariat, of:

Yau K, Kurtesi A, Qi F, Delgado-Brand M, Tursun TR, Hu Q, Dhruve M, Kandel C, Enilama O, Levin A, Jiang Y, Hardy WR, Yuen DA, Perl J, Chan CT, Leis JA, Oliver MJ, Colwill K, Gingras AC, Hladunewich MA. Omicron variant neutralizing antibodies following BNT162b2 BA.4/5 versus mRNA-1273 BA.1 bivalent vaccination in patients with end-stage kidney disease. Nat Commun. 2023 Sep 27;14(1):6041. doi: 10.1038/s41467-023-41678-9.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in Nature Communications, found that Pfizer (BNT162b2 (BA.4/BA.5)) and Moderna (mRNA-1273 (BA.1)) bivalent vaccines induced similar neutralization to each other against Omicron subvariants BA.1, BA.5, BQ.1.1, and XBB.1.5 in patients on dialysis or with a kidney transplant, despite being antigenically divergent from strains circulating at the time. The study was led by Dr. Michelle Hladunewich (University of Toronto) in collaboration with Drs. Adeera Levin (University of British Columbia), Matthew Oliver (University of Toronto), and Anne-Claude Gingras (Lunenfeld-Tanenbaum Research Institute at Sinai Health).

Key findings:

  • Neutralization against Omicron BA.1, BA.5, BQ.1.1, and XBB.1.5 increased by approximately eight-fold one month following bivalent vaccination, providing significant protection, though it was much lower than against the wild-type ancestral strain of SARS-CoV-2. In effect, neutralizing antibodies against Omicron-specific variants were 7.3-fold lower against BA.1, 8.3-fold lower against BA.5, 45.8-fold lower against BQ.1.1, and 48.2-fold lower against XBB.1.5 compared to neutralizing antibodies against the wild type.
  • Viral neutralization was not significantly different by bivalent vaccine type (Pfizer or Moderna) for wild-type, BA.1, BA.5, BQ.1.1, nor XBB.1.5.
  • One month following bivalent vaccination, kidney transplant recipients (n = 15) had significantly lower absolute neutralizing antibody levels than hemodialysis patients (n = 83) against BA.1, BQ.1.1, and XBB.1.5, but not against wild-type or BA.5.
  • Hybrid immunity conferred higher neutralizing antibodies against all Omicron subvariants. Omicron-specific neutralizing antibodies were significantly higher against wild-type, BA.1, BA.5, BQ.1.1, and XBB.1.5 among those who were positive for anti-nucleocapsid antibodies.

This study characterizes neutralization against Omicron subvariants in 98 individuals on dialysis or with a kidney transplant. The median age of this cohort was 70 years and 35% were female. The bivalent COVID-19 vaccine was the fifth overall dose in 92% of participants, with 73% (72/98) of all participants receiving the Moderna bivalent vaccine and 27% (26/98) receiving the Pfizer bivalent vaccine.

Among participants, 26% (25/98) had prior confirmed COVID-19, as determined by RT-PCR or rapid antigen testing, while 41% (40/98) had infection-acquired antibodies before receiving the bivalent vaccination. At one month follow-up, 37% (36/98) had infection-acquired antibodies. There was one new seroconversion, while five individuals who were initially seropositive became seronegative.

Overall, these results on responses to vaccination in patients with end-stage kidney disease are encouraging. Chronic kidney disease is a major risk factor for serious COVID-19 and hemodialysis can increase risk of exposure to SARS-CoV-2.