A new study on Tuesday showed that a key player in the immune response, called the "killer T cell," recognized the coronavirus and remains active against it.
The study results were published in the Open Forum Infectious Diseases, an Oxford University Press journal.
Scientists at the National Institutes of Health (NIH) and Johns Hopkins University collected and analyzed the blood cell samples from 30 people who had contracted but recovered from Covid-19 before the emergence of virus variants.
They checked if these cells, whose technical name is "CD8+ T cells," could still identify the three variants of SARS-CoV-2: B.1.1.7, first found in Britain, B.1.351, identified in South Africa, and B.1.1.248, first seen in Brazil.
Each of these variants is unique because they have mutations in the region of the virus called spike protein, allowing it to invade cells easily and make some variants less recognizable to neutralizing antibodies or the proteins produced by the B cells to fight the infection.
Among the 30 participants in the study, the researchers found that their CD8+ T-cell responses remained largely intact and could recognize virtually all the mutations in the variants studied.
Killer T cells find the telltale signs of cells that have already been infected with pathogens they have previously encountered and destroy those cells.
Though the researchers said that more studies are needed to confirm the results, the study has shown that killer T cells are less susceptible to mutations in the coronavirus than neutralizing antibodies are.