Clinical predictors of SARS-CoV-2 vaccine immunogenicity in kidney transplant recipients at a rural center.

BACKGROUND

Kidney transplant recipients (KTR) have impaired immune responses to vaccination and remain at increased risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection despite mRNA coronavirus disease 2019 (COVID-19) vaccination. Data from rural and medically underserved transplant populations remain limited.

AIM: To evaluate serologic response to a two dose mRNA SARS-CoV-2 vaccination series and identify clinical factors associated with antibody response in KTR.

METHODS

This single center retrospective observational study included adult KTR who completed a two dose mRNA COVID-19 vaccination series and had post vaccination anti spike IgG testing performed using stored serum samples. Multivariable logistic regression was used to identify predictors of seroconversion. Among responders, linear regression was used to evaluate factors associated with quantitative antibody titers.

RESULTS

A total of 108 KTR were included, of whom 63 (58.3%) achieved seroconversion. Higher estimated glomerular filtration rate showed independent association with seroconversion, while higher mycophenolic acid dose showed inverse association with response. Black race and basiliximab induction demonstrated association with seroconversion, though estimates were imprecise. Age, sex, body mass index, vaccine type, tacrolimus levels, and comorbidities were not independently associated with response. Among responders, no clinical or demographic variables were significantly associated with antibody titers.

CONCLUSION

After two dose mRNA vaccination, fewer than two thirds of KTR developed detectable anti spike antibodies. Serologic response was associated with allograft function and antimetabolite exposure, while antibody magnitude was not explained by routine clinical factors in this cohort. These findings provide real world data from a rural transplant population and support consideration of augmented vaccination strategies in KTR.