Booster dose of mRNA vaccine augments waning T cell and antibody responses against SARS-CoV-2

• DOI: 10.3389/fimmu.2022.1012526
• Publication Date: 2022-10-12T09:09:07Z
• Authors: Feyza Gül Özbay Kurt; Alisa Lepper; Catharina Gerhards; Mathis Roemer; Samantha Lasser; Ihor Arkhypov; Rebekka Bitsch; Peter Bugert; Peter Altevogt; Cécile Gouttefangeas; Michael Neumaier; Jochen Utikal; Viktor Umansky
• Keywords: 0301 basic medicine; SARS-CoV-2; Immunology; COVID-19; Viral Vaccines; RC581-607; T cell response; 3. Good health; vector vaccine; 03 medical and health sciences; mRNA vaccine; Antibody Formation; antibodies; Humans; mRNA Vaccines; Immunologic diseases. Allergy; booster dose

A gradual decay in humoral and cellular immune responses over time upon SAR1S-CoV-2 vaccination may cause a lack of protective immunity. We conducted a longitudinal analysis of antibodies, T cells, and monocytes in 25 participants vaccinated with mRNA or ChAdOx1-S up to 12 weeks after the 3rd (booster) dose with mRNA vaccine. We observed a substantial increase in antibodies and CD8 T cells specific for the spike protein of SARS-CoV-2 after vaccination. Moreover, vaccination induced activated T cells expressing CD69, CD137 and producing IFN-γ and TNF-α. Virus-specific CD8 T cells showed predominantly memory phenotype. Although the level of antibodies and frequency of virus-specific T cells reduced 4-6 months after the 2nd dose, they were augmented after the 3rd dose followed by a decrease later. Importantly, T cells generated after the 3rd vaccination were also reactive against Omicron variant, indicated by a similar level of IFN-γ production after stimulation with Omicron peptides. Breakthrough infection in participants vaccinated with two doses induced more SARS-CoV-2-specific T cells than the booster vaccination. We found an upregulation of PD-L1 expression on monocytes but no accumulation of myeloid cells with MDSC-like immunosuppressive phenotype after the vaccination. Our results indicate that the 3rd vaccination fosters antibody and T cell immune response independently from vaccine type used for the first two injections. However, such immune response is attenuated over time, suggesting thereby the need for further vaccinations.