Table 1 Inclusion and Exclusion Criteria for Study Selection.

Assay reported from January 1st, 2020, till May 26th, 2022, examining the human T cell response against the SARS-CoV-2 ancestral spike protein.

Studies analyzing pre-pandemic samples, non-spike-specific response, studies examining subsets besides CD4+ and CD8 + T cells; studies in animal models; assays where expanded T cells were used.

Non-peer reviewed pre-prints

AIM

AIM assay performed between January 1st, 2020, till May 26th^, 2022, examining the surface expression of activation markers CD137 and OX40 on CD4+, and CD137 and CD69 on CD8 + T cells, upon stimulation with the SARS-CoV-2 ancestral (Wuhan isolate) spike protein.

Pre-pandemic (unexposed/unvaccinated), activation markers in subsets besides CD3 + CD4+ or CD3 + CD8+, surface markers besides CD137 and OX40 on CD4+ cells and CD137 and CD69 on CD8+ cells, surface markers for activation + intracellular cytokines, non-spike stimulation, single peptide stimulation, antigen-induced expansion of PBMC or long-term cultures (>48 h)

ELISPOT

Interferon gamma (IFNγ) ELISPOT assay reported between January 1st, 2020, till May 26th, 2022, examining the human T cell response against the SARS-CoV-2 ancestral spike protein.

Datasets reporting IFNγ ELISPOT response in PBMC samples of pre-pandemic unexposed/ unvaccinated individuals, sample size of fewer than three donors, or studies exclusively examining elderly populations. Datasets reported for PBMCs stimulated by a single peptide, non-spike peptide pools, whole protein

ELISPOT data from studies that examined the T cell response <1 month after vaccination.

S2 peptide pools were used for T cell stimulation.

ICS

Published data from Phase I/II/III/IV clinical trials, and efficacy examining the immunogenicity of any of the WHO EUL (Emergency Use Listing) vaccines until 25/05/2022 by ICS.

Datasets from non-WHO EUL vaccine efficacy study. Studies that do not evaluate vaccine efficacy.