Interesting discussion on T-cells. All vaccines for SARS-CoV-2 rely upon antibody excitation; but, there is little discussion on peptide-based vaccines. I found one that is being tested:
https://www.news-medical.net/news/20201203/Novel-e2809cmultitopee2809d-vaccine-shows-promise-in-the-fight-against-COVID-19.aspx
