As the new Omicron variant is said to have mutations that may be helping it escape the body’s first line of defence, antibodies, studies have highlighted a bigger role that the immune system’s second line of defence, T-cells, may play. T cells, the body's weapon against virus-infected cells, were primed enough by vaccination that they defended against Omicron, separate studies have found.

from Times of India https://timesofindia.indiatimes.com/home/science/explainer-t-cells-stands-on-guard-against-omicron-as-antibodies-fail/articleshow/88611157.cms