Kidney transplant recipients see lower IgG production after COVID-19 jab

Vaccination against COVID-19 seems to be less effective among kidney transplant recipients, according to a recent study. Cessation or reduction of immunosuppressive treatments may help increase the production of immunoglobulin (Ig)G in these patients.

In 151 kidney transplant recipients, the mean level of anti-Spike protein IgGs was 1,377 AU/mL. This was significantly lower than that in the 74 live kidney donors and 50 healthy volunteers enrolled as comparators (8,310 and 9,908 AU/mL, respectively; p<0.01 for both). [Int J Urol 2022;doi:10.1111/iju.15027]

Of note, none of the participants in both comparator groups were considered to have negative antibody levels, whereas 32.7 percent of transplant recipients were categorized as such. Meanwhile, 100 percent and 98.6 percent of healthy volunteers and donors had strongly positive antibody levels, respectively, while only 26.7 percent of recipients met such criteria.

Crude analysis showed that women were more likely to be positive for antibodies after COVID-19 vaccination. Cessation of the immunosuppressive mycophenolate mofetil (MMF) treatment correlated with better antibody response, as did younger age, higher lymphocyte count, and better kidney function.

In addition, having prior history of antithymocyte globulin (ATG) treatment was associated with poor response after vaccination.

Multivariate nominal logistic regression analysis was then performed to identify independent indicators of anti-spike IgG positivity. Cessation or dose reduction of MMF remained a significant predictor of better vaccine response, increasing the odds of antibody positivity by nearly four times (odds ratio [OR], 3.78, 95 percent confidence interval [CI], 1.59–9.01; p=0.003).

Strong IgG positivity, defined as titres ≥1,000 AU/mL, was also influenced by MMF reduction or cessation, which improved its odds by more than eight times (OR, 8.24, 95 percent CI, 2.27–24.45; p<0.001).

“Although MMF withdrawal for prolonged period increases the risk of rejection and deterioration of graft survival, cessation of MMF for 3 to 7 days did not result in any rejection episode within the 6 months after the second vaccination,” the researchers said, cautioning that the long-term effects of scaling back immunosuppression remains unknown.

Kidney function, as measured by estimated glomerular filtration rate, also remained significantly and positively associated with general (OR, 16.1, 95 percent CI, 1.08–238.95; p=0.01) and strong (OR, 47.9, 95 percent CI, 2.20–1,044.93; p=0.01) IgG positivity. These results indicate that poor graft function also compromises patient immunity and therefore antibody production after vaccination.

Lymphocyte count also remained a positive predictor of strong IgG response, while having no history of ATG or rituximab treatment correlated with better response overall.

“A higher antibody titre is needed to protect against infection with the Omicron variant; thus, it is important to find ways to enhance antibody production in kidney transplant recipients,” the researchers said. “Approaches for achieving effective antibody production after additional doses of vaccine may also be important, and our strategy of MMF dose modification is useful in this regard.”

Such a strategy could also help improve patient response to other existing vaccines or vaccines that may be developed in the future, they added.