Robust SARS-COV-2-specific T-cell immune memory persists long-term in immunocompetent individuals post BNT162b2 double shot

Anastasia Papadopoulou; Fani Stavridou; Maria Giannaki; Kiriaki Paschoudi; Fani Chatzopoulou; Eleni Gavriilaki; Grigorios Georgolopoulos; Achilles Anagnostopoulos; Evangelia Yannaki

doi:10.1016/j.heliyon.2022.e09863

Robust SARS-COV-2-specific T-cell immune memory persists long-term in immunocompetent individuals post BNT162b2 double shot

Heliyon. 2022 Jul;8(7):e09863. doi: 10.1016/j.heliyon.2022.e09863. Epub 2022 Jul 2.

Authors

Anastasia Papadopoulou¹, Fani Stavridou¹, Maria Giannaki¹, Kiriaki Paschoudi¹, Fani Chatzopoulou², Eleni Gavriilaki¹, Grigorios Georgolopoulos¹, Achilles Anagnostopoulos¹, Evangelia Yannaki¹

Affiliations

¹ Hematology Department- Hematopoietic Cell Transplantation Unit, Gene and Cell Therapy Center, "George Papanikolaou" Hospital, Thessaloniki, Greece.
² Microbiology Department, Aristotle University of Thessaloniki, Greece.

Abstract

Background: A robust efficiency of mRNA vaccines against coronavirus disease-2019 has been demonstrated, however, the intended long-term protection against SARS-CoV-2 has been challenged by the waning humoral and cellular immunity over time, leading to a third vaccination dose recommendation for immunocompetent individuals, six months after completion of primary mRNA vaccination.

Methods: We here measured humoral responses via an immunoassay measuring SARS-CoV-2 neutralizing antibodies and T-cell responses using Elispot for interferon-γ 1- and 8- months post full BNT162b2 vaccination, in 10 health-care professionals. To explore whether the declining abundance of coronavirus-specific T-cells (CoV-2-STs) truly reflects decreased capacity for viral control, rather than the attenuating viral stimulus over time, we modeled ex vivo the T-cellular response upon viral challenge in fully vaccinated immunocompetent individuals, 1- and 8-months post BNT162b2.

Findings: Notwithstanding the declining CoV-2-neutralizing antibodies and CoV-2-STs, re-challenged CoV-2-STs, 1- and 8-months post vaccination, presented similar functional characteristics including high cytotoxicity against both the unmutated virus and the delta variant.

Interpretation: These findings suggest robust and sustained cellular immune response upon SARS-CοV-2 antigen exposure, 8 months post mRNA vaccination, despite declining CοV-2-STs over time in the presence of an attenuating viral stimulus.

Keywords: COVID-19; Ex vivo model; Humoral immune response; SARS-CoV-2; SARS-CoV-2-specific T cells; T cell immune response.