Memory T cells as an occupying force.

There is debate over whether effective T-cell mediated protection against a second infection, or post-vaccination, is better done by central memory cells or effector memory cells. The former may have greater powers of expansion, whereas the latter may be closer to the site of pathogen entry and faster to respond. This review focuses on memory T cells which are not recirculating but which remain at the peripheral site of initial pathogen or vaccine encounter, so-called tissue-resident memory cells. They may play key roles in protection against re-eruption of latent viral infections and at mucosal surfaces.