According to new research published in the journal Cell, T cells may not work well against the Omicron variant in some individuals. 

Researchers evaluated 76 volunteers and noted that in most of them, T cells continued to defend against the Omicron variant even when their antibodies did not, irrespective of the source of the antibodies, including from booster vaccine doses. 

However, nearly 20% of the study participants had over 50% reduction in their T cell response to Omicron, in comparison with previous variants. This could mean that SARS-CoV-2 can evolve to escape T cells, so constant work is needed on vaccines that may be resistant to future variants, said Dr. Gaurav Gaiha of the Ragon Institute of MGH, MIT and Harvard. He added that it is important to take precautions, like mask-wearing and testing.

Gaiha also noted that vaccine boosters increased the T cell response to Omicron by 20-fold… (Reuters, February 12, 2022)