Influenza Vaccination in Solid Organ Transplant Recipients: Methods to Improve Immunogenicity and Future Directions

Abstract Purpose of Review To review the recent literature surrounding immune responses to influenza vaccination in solid organ transplant (SOT) recipients, in addition to reviewing future directions for novel vaccine technologies to help improve immunogenicity in this vulnerable population. Recent Findings While organ transplantation remains a lifesaving treatment for those with organ failure, infections account for many complications in the post-transplant period. Influenza virus is the most common vaccine-preventable illness, but organ transplant recipients often mount an inferior immune response to vaccination compared to the general population. Due to their impaired immune responses to vaccinations, various studies have examined utilizing different strategies to increase immunogenicity to influenza vaccines in this patient population, including the use of booster doses, high-dose vaccines, and vaccines with adjuvants. Trials with high-dose influenza vaccines and booster doses have shown increased immunogenicity when compared to single standard-dose influenza vaccine. Although these strategies may improve immune responses to influenza vaccines to variable degrees, it is still unknown what the optimal method to provide protection against influenza infection in SOT recipients is. While more studies need to be conducted in the SOT population, there is promising new influenza vaccine technology development with mRNA vaccines, universal influenza vaccines, and monoclonal antibodies. Summary As SOT recipients exhibit reduced immunity to vaccines, efforts to increase immunogenicity to influenza vaccine in the transplant population have focused on adjuvanted vaccines, booster doses, and high-dose vaccines. Future directions in this field include mRNA influenza vaccines, universal influenza vaccines, and monoclonal antibodies, but there is no definitive timeline for these products to become available at this time. The authors of this study favor a high-dose influenza vaccination approach for organ transplant recipients, due to ease of administration and demonstrated favorable safety profile.