New COVID-19 Test Detects Cell Mediated (T Cell) Immune Response to SARS-CoV-2 Infection

A new COVID-19 test for the qualitative detection of a cell mediated (T cell) immune response to SARS-CoV-2 in human whole blood has just been launched.

Oxford Immunotec Global PLC (Oxford, UK) has launched the T-SPOT.COVID test, a CE marked ELISPOT based test intended for qualitative detection of a cell mediated (T cell) immune response to SARS-CoV-2 in human whole blood. The company developed the T-SPOT.COVID test as an evolution of its T-SPOT Discovery SARS-CoV-2 assay, a research use only test used to gain insights about the immune response to SARS-CoV-2. Oxford Immunotec has filed an EUA request to the FDA for the test.

Serology does not give the full picture of the adaptive immune response to SARS-CoV-2 infection. Antibodies are not always produced in response to SARS-CoV-2 infection, or may be delayed. Antibodies can also wane quickly after infection and reports show T cells may be more long lived than the antibody response. In the absence of an antibody response, the T cell response may be protective from SARS-CoV-2 infection.

In a clinical study using samples collected in the US, the T-SPOT.COVID test was proven to detect a SARS-CoV-2 cell mediated (T cell) immune response in PCR positive individuals, even with negative serology test results6. The T-SPOT.COVID test therefore, complements results obtained by antibody serology to give a more comprehensive view of an individual's adaptive immune response to SARS-CoV-2 infection. The test could also be used, for example, alongside serology tests to support clinical assessment of individuals who present with suspected COVID-19 but are PCR negative.

In the study, the T-SPOT.COVID test had a positive agreement with PCR-results of 96.6% (84/87) in SARS-CoV-2 infected individuals <60 days after first PCR positive result. At >60 days (with the furthest time point after first positive PCR test result being >240 days) positive agreement remained high at 83.3% (40/48). The T-SPOT.COVID test detected substantially more people with previous positive PCR results than serology in the cohort, whose positivity rate was lower and declined faster over time.

In an endemic cohort of US individuals selected to be at a relative lower risk of SARS-CoV-2 infection (based on the absence of self-reported symptoms, negative serology results and no prior history of a positive PCR test result for SARS-CoV-2) the T-SPOT.COVID test had a negative agreement of 98.0% (96/98). However, there is a possibility that a proportion of this group had, or still have, an asymptomatic infection, seronegative at the time of testing, but in whom the T-SPOT.COVID test was able to detect a T cell response.

"T cells and antibodies are two arms of the adaptive immune response. The detection and measurement of each can provide different insights about disease activity and an individual's personal immunity," said Phill Keefe, Senior VP, Product Design, Development and Delivery at Oxford Immunotec.

"The T-SPOT® Technology platform is a standardized way of measuring T cells. It has been proven in clinical use for over 18 years with another major infectious disease, tuberculosis, which kills around 1.5 million people every year," said Dr. Peter Wrighton-Smith, CEO of Oxford Immunotec. "Our T-SPOT.COVID test is tailored specifically for the detection and measurement of an individual's T cell response to SARS-CoV-2 infection. Having the ability to determine an individual's immune response to SARS-CoV-2 has the potential to support a wide range of needs in our battle against the COVID-19 pandemic."

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