Why do inactivated vaccines typically induce mainly humoral immune responses instead of strong cell-mediated (CD8+ T cell) responses?

Because inactivated vaccines produce large quantities of viral proteins inside host cytosol, which are preferentially processed for MHC I presentation and drive humoral immunity.

Because inactivated vaccines always include adjuvants that solely stimulate B cells directly without engagement of antigen-presenting cells and T cells.

Because inactivated vaccines enter cells and integrate into host genomes, which causes immune tolerance and favors antibody generation rather than T cell activation.

Because inactivated antigens are taken up and presented primarily on MHC II by antigen-presenting cells, favoring CD4+ helper T cell activation and B cell antibody production rather than cytosolic antigen processing needed for strong CD8+ responses.