# Safety and Efficacy of Influenza Vaccination in Kidney Graft Recipients in Late Period After Kidney Transplantation

## TL;DR

This study shows that influenza vaccination is safe and effective for kidney transplant recipients, reducing serious infections without harming graft function.

## Contribution

The study provides evidence for the safety and efficacy of influenza vaccination in kidney transplant recipients post-transplant.

## Key findings

- Vaccinated recipients had significantly fewer serious infections compared to non-vaccinated recipients.
- The vaccine induced a greater increase in Influenza A IgM and Influenza B IgG antibody levels.
- No severe adverse events or graft function deterioration were observed in the vaccinated group.

## Abstract

Background/Objectives: Influenza is a viral infection affecting up to 20% of the general population annually. Solid organ transplant recipients have a higher morbidity and mortality risk, as well as a greater likelihood of severe disease complications. Vaccination against the influenza virus is a safe and recommended prophylaxis; however, immunosuppression and high comorbidity burdens impair the immune response. We assessed the efficacy, safety, and humoral response to influenza vaccine in a population of kidney transplant recipients (KTx). Methods: Adult KTx recipients at least 6 months post-KTx were divided into vaccinated (vKTx) and non-vaccinated (nvKTx) groups based on consent for vaccination. The vKTx group received one dose of quadrivalent split virion inactivated vaccine (Vaxigrip Tetra Sanofi Pasteur). Subjective symptoms and side effects were recorded in paper journals. Antibody levels were assessed with ELISA prior to and 3 months following vaccination. Serum creatinine and proteinuria were assessed prior to vaccination as well as 3 and 6 months after. Results: Of 450 recruited KTx recipients, 91 in the vKTx group and 36 in the nvKTx group of comparable age, KTx vintage, and graft function were included in the study. Graft function and proteinuria remained stable in both groups. The vKTx group experienced no severe adverse events. The most common complaints were general malaise (20.5%) and injection site pain (10.3%). Overall infection rates were comparable, yet the vKTx group experienced significantly fewer serious infections (11.4% vs. 32.3%, p = 0.01); the vKTx group showed a greater increase of Influenza A IgM (p = 0.05) and Influenza B IgG (p = 0.01) compared with the nvKTx group. Conclusions: Influenza vaccination prevents severe infections in KTx recipients, with good serological response and no impact on graft function or severe adverse events.