Response of transplant recipients to influenza vaccination based on type of immunosuppression: A meta-analysis

Influenza vaccination is widely used in transplant recipients, but there is little known about the significance and correlating factors of its effectiveness. In the current study, we reviewed the existing literature on clinical trials performed in transplant recipients on the effectiveness of influenza vaccination and to evaluate the relevance of the type of immunosuppression employed in these patients on the humoral reaction to the vaccine. A comprehensive search of the literature was performed through Pubmed and Google Scholar to find reports indicating immunogenicity of influenza vaccination in transplant patients. Finally, data from 15 published clinical trials were included in the meta-analysis. Data of 947 transplant recipients retrieved from 15 clinical trials investigating the immunogenicity of influenza vaccination were analyzed in this meta-analysis. Analysis showed significantly lower rates of sero-conversion among transplant recipients receiving mycophenolate mofetil (MMF) than other immunosuppressive agents (relative risk: 0.724; 95% confidence interval: 0.596-0.880; P = 0.001). No significant correlation was found with tacrolimus, sirolimus, cyclosporine and azathioprine. Different immunosuppressive agents seem to have different effects on the humoral response rate to influenza vaccination, with MMF having the most significant deleterious effect. The limited and controversial data available in the literature do not support any differential effect for other immunosuppressive agents.