The current mRNA and viral vectored recombinant vaccines are already very good at stimulating a cytotoxic T cell response. People are always talking about antibodies, because they are easy to measure and do give an indication of a vaccine’s effectiveness. But it’s the T cells that do the heavy lifting, by clearing out virus infected cells before they can pump out more virus. These types of vaccines can induce a T cell response fairly quickly, as in less than two weeks. That’s why one shot of these types of vaccines can be partially protective within a week or two after administration and before any IgG is produced.