The 'Killer' That Catches Omicron Was Not Antibodies but T Cells [Reading Science]

T cells, a type of lymphocyte responsible for cellular immunity within the human body. Source=Nature

[Asia Economy Reporter Kim Bong-su] There is a growing call to focus research on 'T cells,' which are responsible for the body's natural immune function and have emerged as a key weapon in preventing severe illness in response to COVID-19 variants such as Omicron. As the Omicron variant has been confirmed to be highly infectious but less virulent, it is expected that the COVID-19 pandemic will shift from preventing the spread of infection to reducing the number of deaths, transitioning into an 'endemic' phase. This has drawn significant attention.

According to the international journal Nature on the 13th, scientists worldwide have recently reported that COVID-19 variants, including Omicron, are vulnerable to T cell responses.

When the COVID-19 virus initially spread, scientists focused on the body's immune system producing 'antibodies' that attach to and neutralize the virus upon invasion. Antibodies were easier to analyze than T cells, making them the focus of international vaccine development research. However, as the COVID-19 virus continues to mutate, the vulnerability of antibody-based immunity has become apparent. The variants extensively alter the spike protein, which binds to human cells, thereby evading the antibody defense network.

However, T cells have been different. They faithfully perform immune functions, including acting as 'killer' cells that destroy viruses and infected cells within the body. With T cells performing their role, the spread of infection is limited, and the rate of severe illness is reduced. Notably, compared to antibodies produced after vaccination or infection, T cells do not disappear easily. They also remember the spike protein of COVID-19 viruses more extensively than antibodies, allowing immune responses to continue despite mutations.

The role of T cells is particularly significant against the Omicron variant. Some studies have confirmed that the target sites recognized by T cells and the mutation sites of Omicron coincide. Other studies have found that T cells taken from people previously infected with earlier variants or vaccinated respond to the Omicron variant.

Experts also believe that the prevention of severe illness in people vaccinated with Pfizer, Moderna, Janssen, and other vaccines upon Omicron infection may be due to the role of T cells. Dan Barouch, director of the Harvard Medical School's Center for Virology and Vaccine Research, said, "None of these vaccines produced neutralizing antibodies against Omicron," adding, "The efficacy data from South Africa (in preventing severe illness) is likely due to T cells."

COVID-19 vaccine researchers acknowledge that there was a lack of proper research and analysis. Harlan Robins, co-founder of Adaptive Biotechnologies in Seattle, USA, said, "In the initial large-scale vaccine trials conducted on adults, there was not enough sample collection to analyze the relationship between T cell responses and vaccine efficacy."

Therefore, there are calls to focus research on the function and role of T cells in preparation for future emerging variants. Corine Geurts van Kessel, a clinical virologist at Erasmus Medical Center in Rotterdam, the Netherlands, said, "As countries worldwide shift their focus from preventing infection spread to preventing severe illness and as new variants emerge, T cells will receive more attention. If the goal is infection prevention, antibodies are a more important tool, but if the focus is on preventing severe illness, research on T cells is more crucial."