Cellular, or “T-cell,” immunity against Covid-19 is likely to be present within most adults six months after primary infection, a new study said. Research by the U.K. Coronavirus Immunology Consortium (UK-CIC), Public Health England and Manchester University NHS Foundation Trust has found “robust T-cell responses” to the coronavirus six months after infection. T-cells are a part of our immune system that attack cells which have been infected with a virus or other kind of pathogen and they help other antibody-producing cells in the immune system.