Publication date: Oct 01, 2023

The immunogenicity elicited by the Omicron BA. 4/BA. 5-adapted bivalent booster vaccine after solid organ transplantation (SOT) has not been characterized. We assessed cell-mediated and neutralizing IgG antibody responses against the BA. 4/BA. 5 spike receptor-binding domain at baseline and 2 wk after the administration of an mRNA-based bivalent (ancestral strain and BA. 4/BA. 5 subvariants) vaccine among 30 SOT recipients who had received ≥3 monovalent vaccine doses. Previous coronavirus disease 2019 history was present in 46. 7% of them. We also recruited a control group of 19 nontransplant healthy individuals. Cell-mediated immunity was measured by fluorescent ELISpot assay for interferon (IFN)-γ secretion, whereas the neutralizing IgG antibody response against the BA. 4/BA. 5 spike receptor-binding domain was quantified with a competitive ELISA. The median number of BA. 4/BA. 5 spike-specific IFN-γ-producing spot-forming units (SFUs) increased from baseline to 2 wk postbooster (83. 8 versus 133. 0 SFUs/10 peripheral blood mononuclear cells; P = 0. 0017). Seropositivity rate also increased (46. 7%-83. 3%; P = 0. 001), as well as serum neutralizing activity (4. 2%-78. 3%; P 

Semantics

Original Article