AUTHOR=Heinzel Andreas , Schrezenmeier Eva , Regele Florina , Hu Karin , Raab Lukas , Eder Michael , Aigner Christof , Jabbour Rhea , Aschauer Constantin , Stefanski Ana-Luisa , Dörner Thomas , Budde Klemens , Reindl-Schwaighofer Roman , Oberbauer Rainer 

TITLE=Three-Month Follow-Up of Heterologous vs. Homologous Third SARS-CoV-2 Vaccination in Kidney Transplant Recipients: Secondary Analysis of a Randomized Controlled Trial

JOURNAL=Frontiers in Medicine

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.936126

DOI=10.3389/fmed.2022.936126

ISSN=2296-858X

ABSTRACT=<p>Response to SARS-CoV-2-vaccines in kidney-transplant recipients (KTR) is severely reduced. Heterologous3<sup>rd</sup> vaccination combining mRNA and vector vaccines did not increase seroconversion at 4 weeks after vaccination, but evolution of antibody levels beyond the first month remains unknown. We have recently completed a randomized-controlled trial on heterologous (Ad26COVS1) vs. homologous (BNT162b2 or mRNA-1273) 3<sup>rd</sup> vaccination in 201 KTR not developing SARS-CoV-2-spike-protein antibodies following two doses of mRNA vaccine (EurdraCT: 2021-002927-39). Here, we report seroconversion at the second follow-up at 3 months after the 3<sup>rd</sup> vaccination (prespecified secondary endpoint). In addition, higher cut-off levels associated with neutralizing capacity and protective immunity were applied (i.e., &gt; 15, &gt; 100, &gt; 141, and &gt; 264 BAU/ml). A total of 169 patients were available for the 3-month follow-up. Overall, seroconversion at 3 months was similar between both groups (45 vs. 50% for mRNA and the vector group, respectively; <italic>p</italic> = 0.539). However, when applying higher cut-off levels, a significantly larger number of individuals in the vector group reached antibody levels &gt; 141 and &gt; 264 BAU/ml at the 3-month follow-up (141 BAU/ml: 4 vs. 15%, <italic>p</italic> = 0.009 and 264 BAU/ml: 1 vs. 10%, <italic>p</italic> = 0.018 for mRNA vs. the vector vaccine group, respectively). In line, antibody levels in seroconverted patients further increased from month 1 to month 3 in the vector group while remaining unchanged in the mRNA group (median increase: mRNA = 1.35 U/ml and vector = 27.6 U/ml, <italic>p</italic> = 0.004). Despite a similar overall seroconversion rate at 3 months following 3<sup>rd</sup> vaccination in KTR, a heterologous 3rd booster vaccination with Ad26COVS1 resulted in significantly higher antibody levels in responders.</p>