# Comparison of Post-Vaccination Response (Humoral and Cellular) to BNT162b2 in Clinical Cases, Kidney and Pancreas Transplant Recipient with Immunocompetent Subjects over Almost Two Years of Parallel Monitoring

## TL;DR

This study compares the immune response to the BNT162b2 vaccine in transplant recipients and healthy individuals over two years, finding that transplant recipients need booster doses for adequate protection.

## Contribution

The study provides long-term comparative data on humoral and cellular vaccine responses in transplant recipients versus immunocompetent individuals.

## Key findings

- Transplant recipients showed lower antibody levels after primary vaccination compared to immunocompetent individuals.
- A booster dose was needed for transplant recipients to reach antibody levels similar to the control group after baseline vaccination.
- Transplant recipients did not achieve a positive cellular immune response during the monitoring period.

## Abstract

Background: Vaccination is one of the most effective medical interventions to prevent infectious diseases. The introduction of vaccines against coronavirus acute respiratory syndrome 2 (SARS-CoV-2) was aimed at preventing severe illness and death due to coronavirus disease 2019 (COVID-19). Solid organ transplant recipients (SOTRs) are at high risk of infection with SARS-CoV-2 and serious effects associated with COVID-19, mainly due to the use of immunosuppressive therapies, which further cause suboptimal response to COVID-19 vaccination. Aim of the study: We aimed to compare post-vaccination response to BNT162b2 in kidney–pancreas transplant recipient, specifically in immunocompetent individuals, over two years of simultaneous monitoring. Methods: To determine the humoral response, the levels of the IgG and IgA anti-S1 antibodies were measured. To assess the cellular response to SARS-CoV-2, the released IFN-γ-S1 was determinate. Results and Conclusion: After primary vaccination, compared to immunocompetent subjects, SOTR showed lower seroconversion for both antibody classes. Only the additional dose produced antibodies at the level reached by the control group after the baseline vaccination. During the monitored period, SOTR did not achieve a positive cellular response in contrast to immunocompetent individuals, so in order to obtain longer protection, including immune memory, the adoption of booster doses of the vaccine should be considered.