Neutralization of SARS-CoV-2 variants of concern in kidney transplant recipients after standard COVID-19 vaccination

Abstract

Background and objectives: antibody response after severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) vaccination is impaired in kidney transplant recipients. Emerging variants, such as B.1.617.2 ( d), are of particular concern because of their higher transmissibility and partial immune escape. Little is known about protection against these variants in immunocompromised patients. Design, setting, participants, and measurements: in this prospective two-center study, antispike 1 IgG and surrogate neutralizing antibodies were measured in 173 kidney transplant recipients and 166 healthy controls with different vaccination schedules. In addition, different SARS-CoV-2 epitope antibodies from 135 vaccinated kidney transplant recipients were compared with antibodies in 25 matched healthy controls after second vaccination. In 36 kidney transplant recipients with seroconversion, neutralization against B.1.1.7 ( a), B.1.351 ( b), and B.1.617.2 ( d) was determined on VeroE6 cells and compared with neutralization in 25 healthy controls. Results: kidney transplant recipients had significantly lower seroconversion rates compared with healthy controls. After the second vaccination, antispike 1, antireceptor-binding domain, and surrogate neutralizing antibodies were detectable in 30%, 27%, and 24% of kidney transplant recipients, respectively. This compares with 100%, 96%, and 100% in healthy controls, respectively (P,0.001). Neutralization against B.1.1.7 was detectable in all kidney transplant recipients with seroconversion, with a median serum dilution that reduces infection of cells by 50% of 80 (interquartile range, 80-320). In contrast, only 23 of 36 (64%) and 24 of 36 (67%) kidney transplant recipients showed neutralization against B.1.351 and B.1.617.2, respectively, with median serum dilutions that reduce infection of cells by 50% of 20 (interquartile range, 0-40) and 20 (interquartile range, 0-40), respectively. Neutralization against different variants was significantly higher in healthy controls (P,0.001), with all patients showing neutralization against all tested variants. Conclusions: seroconverted kidney transplant recipients show impaired neutralization against emerging variants of concern after standard two-dose vaccination.