Background: Belatacept may impair humoral immunity, impacting the effectiveness of SARS-CoV-2 mRNA vaccines in transplant recipients. We investigated immunogenicity after SARS-CoV-2 mRNA vaccines in kidney transplant recipients who are and are not taking belatacept.
Methods: Participants were recruited between December 9, 2020, and April 1, 2021. Blood samples were collected after dose 1 and dose 2 (D1, D2) and analyzed using either an anti-SARS-CoV-2 enzyme immunoassay against the S1 domain of the SARS-CoV-2 spike protein or immunoassay against the receptor-binding domain of the SARS-CoV-2 spike protein. Stabilized inverse probability of treatment weights was used to compare immunogenicity, and a weighted logistics regression was used to calculate fold change of positive response.
Results: Among the 609 participants studied, 24 (4%) were taking belatacept. After dose 1, 0/24 (0%) belatacept patients had detectable antibodies, compared with 77 of 568 (14%) among the equivalent nonbelatacept population (P = 0.06). After dose 2, 1/19 (5%) belatacept patients had detectable antibodies, compared with 190/381 (50%) among the equivalent nonbelatacept population (P < 0.001). Belatacept use was associated with 16.7-fold lower odds of having a positive post-D2 titer result (P < 0.01).
Conclusions: Additional measures need to be explored to protect kidney transplant recipients taking belatacept. Best safety practices should be continued despite vaccination among this population.
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