The T-cell test bronze goes to Qiagen
Qiagen today became the third company to launch a T-cell-based test for prior Covid-19 infection and also to assess individuals’ response to vaccination. The Quantiferon Sars-Cov-2 assay, which detects CD4+ and CD8+ T-cell responses elicited by the virus, is now available in Europe, joining Perkinelmer’s T-Spot Discovery Sars-CoV-2 product. Neither of these is yet available in the US, however, where the only T-cell test with FDA emergency authorisation is Adaptive Biotechnologies’ T-Detect Covid assay. Qiagen says its blood test, which has grown out of the Dutch group’s year-old collaboration with Tscan Therapeutics, is differentiated from the competition as it does not require a purification step for the lymphocytes. Testing for Covid-19-reactive T-cells is believed to be a useful adjunct to antibody testing since the response declines more slowly than antibody response, but also appears beforehand, since CD4+ T-cells help B cells generate anti-Covid antibodies. Quantiferon Sars-Cov-2 could indicate how severe the course of a Covid infection will be, according to Qiagen, as well as how long immunity might last. But there is as yet no definitive evidence linking T-cell readings to resistance to subsequent infection with Covid-19.
|Marketed Covid-19 T-cell tests|
|Perkinelmer||T-Spot Discovery Sars-CoV-2||CE marked Mar 2021; awaiting US EUA|
|Adaptive Biotechnologies||T-Detect Covid||US EUA granted Mar 2021|
|Qiagen||Quantiferon Sars-Cov-2||CE marked Dec 2021|
|Source: FDA, company releases.|