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Abstract: TH-PO915

Humoral Responses in the Omicron Era Following a Three-Dose SARS-CoV-2 Vaccine Series in Kidney Transplant Recipients

Session Information

Category: Coronavirus (COVID-19)

  • 000 Coronavirus (COVID-19)

Authors

  • McEvoy, Caitríona M., St. Michael's Hospital Keenan Research Centre for Biomedical Science, Unity Health Toronto, Toronto, Ontario, Canada
  • Hu, Queenie, Lunenfield-Tanenbaum Research Institute, Toronto, Ontario, Canada
  • Abe, Kento T., Lunenfield-Tanenbaum Research Institute, Toronto, Ontario, Canada
  • Yau, Kevin, Division of Nephrology, Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  • Oliver, Matthew J., Division of Nephrology, Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  • Levin, Adeera, UBC Division of Nephrology, St. Paul's Hospital, Vancouver, British Columbia, Canada
  • Gingras, Anne-Claude, Lunenfield-Tanenbaum Research Institute, Toronto, Ontario, Canada
  • Hladunewich, Michelle A., Division of Nephrology, Department of Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  • Yuen, Darren A., St. Michael's Hospital Keenan Research Centre for Biomedical Science, Unity Health Toronto, Toronto, Ontario, Canada
Background

Kidney transplant recipients (KTR) have a diminished response to SARS-CoV-2 vaccination in comparison to immunocompetent individuals. Deeper understanding of the antibody response in KTRs following third-dose vaccination would enable identification of those who remain unprotected against Omicron and require additional treatment strategies.

Methods

We profiled antibody responses in KTRs pre- and at one and three months post-third-dose SARS-CoV2 mRNA-based vaccine. Anti-spike and anti-RBD IgG levels were determined by ELISA. Neutralization against wild-type, Beta, Delta and Omicron (BA.1) variants was determined using a SARS-CoV-2 spike pseudotyped lentivirus assay.

Results

44 KTRs were analysed at 1 and 3 months (n=26) post-third-dose. At one month, the proportion of participants with a robust antibody response had increased significantly from baseline, but Omicron-specific neutralizing antibodies were detected in just 45% of KTRs. Median anti-spike and anti-RBD antibody levels declined at 3 months, but the proportion of KTRs with a robust antibody response was unchanged. 38.5% KTRs maintained Omicron-specific neutralization at 3 months. No clinical variables were significantly associated with detectable Omicron neutralizing antibodies, but anti-RBD titres appeared to identify those with Omicron-specific neutralizing capacity.

Conclusion

Over 50% of KTRs lack an Omicron-specific neutralization response 1 month following a third mRNA-vaccine dose.Among responders, binding and neutralizing antibody responses were well preserved at 3 months. Anti-RBD antibody titres may be a useful identifier of patients with detectable Omicron neutralizing antibody response.