t-cell vaccine t-cell vaccine a t-cell vaccine is a vaccine designed to induce protective t-cells. for vaccination with t cells, see t-cell vaccination. t-cell vaccines are designed to induce cellular immunity. they are also referred to as cell-mediated immune (cmi) vaccines. it is thought that they can be more effective than conventional b-cell vaccines for protection from microbes that hide inside host cells, and viruses (such as hiv or influenza) that mutate rapidly. t-cell vaccines underwent clinical trials for hiv/aids. as of july 2012 none have been approved. as december 2020, the pfizer-biontech covid jab passed the fda's emergency use authorization and became the first fda authorized t cell vaccine.