First test to identify T Lymphocyte immune response to Covid-19


The Private Harley Street Clinic is the first UK clinic to offer T cell testing to determine previously undetected lymphocyte immune responses to Covid-19 infection or vaccination. 

Hitherto, the only test available to assess an immune response was based on the presence of antibodies in identification of previous Covid-19 infections. However, the new T-SPOT®.COVID test will enable individuals themselves to discover whether they have mounted a T cell immune response to Covid-19 as opposed to an antibody response which is the other way that the immune system deals with Covid-19 viral infection.

Dr Mark Ali, Medical Director of the Private Harley Street Clinic, and a Cardiothoracic Surgeon of 30 years’ experience says: "Identification of a T cell response to Covid-19 is seen as the missing link in testing. We have tracked so many people who are sure that they have had Covid-19 but test negative for antibodies and also the antigen itself, perhaps because they were tested too late to pick up the virus or it was a false negative.

“In these cases, we have long believed that they may have had T Cell immune response, but we have had no method of confirming this – until now. This is a substantial development, helping people to confirm their own Covid-19 immunity status.

“Because of the pandemic’s length and changing mutations people are quite rightly concerned about their Covid-19 status. It is helpful, but also empowering for people to know if they have had Covid-19 and generated an immune response. In time, T Lymphocyte testing may also provide us with a more realistic picture of how many people have had the virus.”

The T-SPOT®.COVID test has been developed by Oxford Immunotec Global PLC producers of the T-SPOT®.TB test, which was originally used for diagnosing infection with Tuberculosis. The test is highly accurate and was positive in 96.6 % of a group of previously infected individuals <60 days after infection and 83.3 % at >60 days after infection:

  • The T-SPOT®.COVID test is available at The Private Harley Street Clinic for £195.00
  • The new ELISPOT based test is intended for qualitative detection of a cell mediated (T cell) immune response to SARS-CoV-2 in human whole blood
  • The T cell test (the T-SPOT.COVID test) is CE marked and registered with the MHRA for use in the UK
  • This requires a venous blood sample taken from a vein by a qualified medical professional
  • For further information  please visit
  • Results are returned within 48 hours

The T cell test is intended to detect a T cell-mediated immune response to Covid-19, which is different to serology which looks for an antibody response. T cells and antibodies are two arms of the adaptive immune response. The detection and measurement of each can provide different information about disease activity and an individual’s immune response. Antibodies may not be present in everyone who gets infected with Covid-19 and they may not be detectable after a long period of time.

If a person is exposed to Covid-19, their immune system will react to start clearing the virus. Part of this response is to produce specific T cells which can either clear virus themselves (Killer T cells – or more correctly cytotoxic T cells), or support the work of other T cells and antibodies (Helper T cells). 

Fresh evidence has emerged to confirm that a T cell response can be measured as early as 10 days after an infection as opposed to the antibody test which is only reliable one month after the infection.

An individual now also has the ability to see if they have an immune response in either or both antibody and lymphocyte arms after suspected infection or vaccination.