Pre-existing influenza antibodies, younger age, and increased CD4 TE+EM predict influenza vaccination responses in transplant recipients.

Recipients of kidney transplants require lifelong immunosuppression therapy which is associated with a reduced response to vaccinations. We conducted a longitudinal study of influenza vaccination in US Veteran kidney transplant recipients and correlated demographic factors and T cell characteristics to the immunological outcome of the vaccination. Our data suggest that a consistent history of annual vaccination during the 3 years prior is linked to an increase in influenza antibodies prior to vaccination. High influenza titers post-vaccination are associated with younger age, increased CD4 TE+EM cells and pre-existing anti-influenza IgG levels but no association of CMV serostatus or immunologically aged T cells was detected. Thus, preexisting IgG antibodies, age, and CD4 TE+EM cells could serve as predictors for the successful influenza vaccination in this at-risk population informing targeted interventions to improve vaccine responses, prevent infections, and reduce influenza-associated comorbidities.