Sunday March 26, 2023 - 10:00 to 11:00
Marco Cazzaniga, Italy has been granted the IPTA Scientific Congress Award
Humoral response to Covid-19 mRNA vaccines in a cohort of young kidney transplant recipients from a single center in Northern Italy
Sara Testa1, Marco Cazzaniga2, Olga Caporale1, Chiara Tamburello1, Massimo Oggioni3, Ferruccio Ceriotti3, Maria Viganoni2, Giovanni Montini4.
1Pediatric Nephrology, Dialysis and Transplantation Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy; 2University of Milan, Milano, Italy; 3Clinical Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milano, Italy; 4Department of Clinical Sciences and Community Health, University of Milan, Milano, Italy
Objectives: To investigate immune-response to COVID-19 vaccines in young kidney transplant (KT) recipients from Northern Italy.
Methods: We prospectively studied KT patients aged 12-25 years, managed in our Center on maintenance IS therapy (corticosteroids, CNI and anti-proliferative agents), eligible for antiSARS-Cov2 vaccination according to the schedule of the Italian Medicines Agency for immunosuppressed patients (two doses plus additional dose one month later). From 1st July 2021 to 28th February 2022 we evaluated antiSpike-protein antibody response at T0 (before vaccine), T1, T2 and T3 (14±3 days after 2nd and 3rd dose and 90±7 days after 3rd dose, respectively) to BNT162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) [Figure 1].
AntiSpike total Ig titer cut-off was 0.8 U/ml (Roche® Elecsys Anti-SARS-CoV-2-S). Exclusion criteria: KT or additional IS within 6 months, relapse of primary disease, vaccine before KT, ongoing COVID-19, patients resident outside the Region.
Results: Eighty-seven patients were eligible; 68 patients were enrolled. Median age: 19.5 (IQR:16.3-21.9) years; median time from KT: 61.4 (IQR: 36.7-111.7) months. Five patients dropped out of study after enrollment.
Anti-SARS-Cov2 Spike Antibodies response to mRNA vaccines is shown in Figure 2.
90% of non-responders at T1 (20 patients) seroconverted at T3. We didn’t find correlation between time from KT (the shorter time, the most intensive immunosuppression) and Ig-titer. Twelve out of 58 pts developed COVID19 after the third additional vaccine dose; in this population AntiSpike Ig titer at T2 was lower compared to the value of non infected patients, even if not statistically significant: 144 U/ml (IQR:9.4-3683) vs. 4771 U/ml (IQR:79.1-13000) respectively. None patient had side effects, including acute rejection episodes or de novo DSA development.
Conclusions: KT pediatric recipients exhibit a satisfactory response after 2 doses of vaccine, that become comparable to that of immunocompetent population after the third. Furthermore, the response after two doses is better if compared with adult KT population (63.6% vs 30-50%).
 Benotmane I, et al Low immunization rates among kidney transplant recipients who received 2 doses of the mRNA-1273 SARS-CoV-2 vaccine. Kidney Int. 2021
 Rozen-Zvi B, et al. Antibody response to SARS-CoV-2 mRNA vaccine among kidney transplant recipients: a prospective cohort study. Clin Microbiol Infect. 2021
 Stumpf J et al. Cellular and Humoral Immune Responses After 3 Doses of BNT162b2 mRNA SARS-CoV-2 Vaccine in Kidney Transplant. Transplantation. 2021