AUTHOR=Heinen Natalie , Marheinecke Corinna Sophie , Bessen Clara , Blazquez-Navarro Arturo , Roch Toralf , Stervbo Ulrik , Anft Moritz , Plaza-Sirvent Carlos , Busse Sandra , Klöhn Mara , Schrader Jil , Vidal Blanco Elena , Urlaub Doris , Watzl Carsten , Hoffmann Markus , Pöhlmann Stefan , Tenbusch Matthias , Steinmann Eike , Todt Daniel , Hagenbeck Carsten , Zimmer Gert , Schmidt Wolfgang Ekkehard , Quast Daniel Robert , Babel Nina , Schmitz Ingo , Pfänder Stephanie TITLE=In-depth analysis of T cell immunity and antibody responses in heterologous prime-boost-boost vaccine regimens against SARS-CoV-2 and Omicron variant JOURNAL=Frontiers in Immunology VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.1062210 DOI=10.3389/fimmu.2022.1062210 ISSN=1664-3224 ABSTRACT=

With the emergence of novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Variants of Concern (VOCs), vaccination studies that elucidate the efficiency and effectiveness of a vaccination campaign are critical to assess the durability and the protective immunity provided by vaccines. SARS-CoV-2 vaccines have been found to induce robust humoral and cell-mediated immunity in individuals vaccinated with homologous vaccination regimens. Recent studies also suggest improved immune response against SARS-CoV-2 when heterologous vaccination strategies are employed. Yet, few data exist on the extent to which heterologous prime-boost-boost vaccinations with two different vaccine platforms have an impact on the T cell-mediated immune responses with a special emphasis on the currently dominantly circulating Omicron strain. In this study, we collected serum and peripheral blood mononuclear cells (PBMCs) from 57 study participants of median 35-year old’s working in the health care field, who have received different vaccination regimens. Neutralization assays revealed robust but decreased neutralization of Omicron VOC, including BA.1 and BA.4/5, compared to WT SARS-CoV-2 in all vaccine groups and increased WT SARS-CoV-2 binding and neutralizing antibodies titers in homologous mRNA prime-boost-boost study participants. By investigating cytokine production, we found that homologous and heterologous prime-boost-boost-vaccination induces a robust cytokine response of CD4+ and CD8+ T cells. Collectively, our results indicate robust humoral and T cell mediated immunity against Omicron in homologous and heterologous prime-boost-boost vaccinated study participants, which might serve as a guide for policy decisions.