Cellular immunity test for SARS-CoV-2

Discover the real power of your immune system!

Following SARS-CoV-2 virus infection or vaccination, the body's adaptive immune response consists of a humoral and cellular response. The humoral part is represented by B lymphocytes which produce antibodies that bind specifically to viral proteins and thus neutralize and destroy the virus. IgA and IgM antibodies are produced at an early stage of the immune response, while IgG antibodies are formed later and can be detected over a longer period.

It has been observed that, in most populations, antibodies disappear rapidly after infection with the SARS-CoV-2 virus or after vaccination and people do not know if they are still protected. An additional problem is that a large number of people who came in contact with SARS-CoV-2 were asymptomatic and never developed antibodies. Such individuals will never actually know if they have gotten over COVID-19 unless it is determined by measuring cellular immunity. In other words, it is recommended that anyone who wants to know whether they are protected from COVID-19 (including people who recovered from COVID-19 and those who have been vaccinated) perform the aforementioned test in order to determine cellular immunity. No other test can fully determine the level of protection against COVID-19, especially if no measurable antibodies are present.

Namely, T lymphocytes are a heterogeneous group of immune cells and participate in the cellular immune response. Cytotoxic T lymphocytes stimulate the self-destruction mechanism of a virus-infected cell and thus prevent viral replication. Helper T lymphocytes can develop into cells with different functions, and they participate in the immune response by interacting with B lymphocytes, which produce antibodies, and cytotoxic T lymphocytes. Exposure to the SARS-CoV-2 virus stimulates the production of interferon-gamma in cytotoxic and helper T lymphocytes, which plays a central role in the defense against the virus by activating macrophages and stimulating specific cytotoxic immunity. This suggests that the cellular response may be a more sensitive indicator of virus exposure than antibodies and that SARS-CoV-2 virus infection may lead to a specific T lymphocyte response beyond antibody production (1). A similar phenomenon was observed in individuals infected with the hepatitis C virus (HCV), where it was established that the cellular response via T lymphocytes is a far more sensitive indicator of HCV exposure compared to antibody production (2). Recently published significant results in the leading scientific journal "Cell" confirm the occurrence of polyfunctional SARS-CoV-2 T lymphocytes in individuals who have been infected with SARS-CoV-2 but have not developed antibodies (3). In addition, cytotoxic and helper T lymphocytes can be converted into memory cells to achieve long-term immunity that will enhance and accelerate the response to infection upon re-exposure to the SARS-CoV-2 virus. Memory T lymphocytes can also stimulate a memory B lymphocyte's antibody production.

You can perform a SARS-CoV-2 cellular immunity test at the St. Catherine Specialty Hospital at Branimirova 71E, Zagreb (booking an appointment is mandatory). The test is performed on a peripheral venous blood sample by stimulating T lymphocytes with SARS-CoV-2 virus S protein components. By doing so, interferon-gamma is released, the concentration of which is measured by ELISA (Euroimmun Interferon-gamma). This test has a high diagnostic sensitivity (97.9%), which is based on the results obtained from the samples of persons who recovered from COVID-19 or received the vaccine. Its high diagnostic specificity (97.8%) was calculated using the results obtained in the samples of persons without a history of SARS-CoV-2 infection (4). The result is expressed as mIU/mL, and all values >200 mIU/mL indicate positive cellular immunity.

Our blood testing package includes a cellular immunity test with a bonus humoral immunity (antibody) test. By testing both components, one gets a complete picture of the body's overall immune defense. According to the latest scientific information, the level of cellular immunity combined with antibody levels provides the most reliable information on the susceptibility to future COVID-19 infections.


• according to all previous scientific information, memory T cells specific to SARS-CoV-2 are crucial for long-term protection against COVID-19,

• recently published scientific papers confirm that cellular immunity (mediated by T cells or T lymphocytes) also exists in a person in whom antibodies against the SARS-CoV-2 virus were not detected, which includes people who recovered from the disease and were either asymptomatic or symptomatic,

• except for the cellular immunity test (mediated by T cells or T lymphocytes), there is no other way to determine that a person had COVID-19 if there are no detectable antibodies to the SARS-CoV-2 virus.


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1. Gallais F, Velay A, Nazon C, Wendling M, Partisani M, Sibilia J, i sur. Intrafamilial Exposure to SARS-CoV-2 Associated with Cellular Immune Response without Seroconversion, France. Emerg Infect Dis. 2021; 27:113-21.

2. Heller T, Werner JM, Rahman F, Mizukoshi E, Sobao Y, Gordon AM, i sur. Occupational exposure to hepatitis C virus: early T-cell responses in the absence of seroconversion in a longitudinal cohort study. J Infect Dis. 2013; 208:1020-5.

3. Sekine T, Perez-Potti A, Rivera-Ballesteros O, Strålin K, Gorin JB, Olsson A, i sur. Robust T Cell Immunity in Convalescent Individuals with Asymptomatic or Mild COVID-19. Cell. 2020; 183:158-68.e14.

4. Huzly D, Panning M, Smely F, Enders M, Komp J, Steinmann D. Validation and performance evaluation of a novel interferon-γ release assay for the detection of SARS-CoV-2 specific T-cell response. medRxiv 2021.07.17.21260316

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