Expansion of cytotoxic tissue-resident CD8(+) T cells and CCR6(+)CD161(+) CD4(+) T cells in the nasal mucosa following mRNA COVID-19 vaccination

Vaccines against SARS-CoV-2 have shown high efficacy in clinical trials, yet a full immunologic characterization of these vaccines, particularly within the human upper respiratory tract, is less well known. Here, we enumerate and phenotype T cells in nasal mucosa and blood using flow cytometry before and after vaccination with the Pfizer-BioNTech COVID-19 vaccine (n = 21). Tissue-resident memory (Trm) CD8(+) T cells expressing CD69(+)CD103(+) increase in number ~12 days following the first and second doses, by 0.31 and 0.43 log(10) cells per swab respectively (p = 0.058 and p = 0.009 in adjusted linear mixed models). CD69(+)CD103(+)CD8(+) T cells in the blood decrease post-vaccination. Similar increases in nasal CD8(+)CD69(+)CD103(−) T cells are observed, particularly following the second dose. CD4(+) cells co-expressing CCR6 and CD161 are also increased in abundance following both doses. Stimulation of nasal CD8(+) T cells with SARS-CoV-2 spike peptides elevates expression of CD107a at 2- and 6-months (p = 0.0096) post second vaccine dose, with a subset of donors also expressing increased cytokines. These data suggest that nasal T cells may be induced and contribute to the protective immunity afforded by this vaccine.