New blood test could improve COVID-19 defenses assessment

Unlike antibodies, T cells do not prevent infection from occurring, "but they protect from disease," said study co-author Dr. Antonio Bertoletti of Duke-NUS Medical School in Singapore, in an email. They "recognize the infected cells... and destroy them. T cells are also important for the efficient maturation of B cells, (which) also help to produce antibodies," he said.

In some people with weakened immune systems, COVID-19 vaccines can induce T cell responses even if they do not induce antibody responses. "Measuring T cell activation is critical to assess the full extent of a person's immunity," said coauthor Ernesto Guccione of The Tisch Cancer Institute at Mount Sinai in a statement. Coronavirus variants like Omicron evade most of the neutralizing ability of antibodies, but T cells are still able to recognize the virus despite the mutations, he noted, making it even more important to have tests that can measure T cells.

The new test is presently available only for research purposes but is scalable to use broadly in the population, the researchers reported on Monday in Nature Biotechnology.