Measuring T-cell response could be a more reliable indication of how coronavirus is spreading in the community than antibody testing, scientists have said.
T-cells can wipe out viruses if usual immune cells are unsuccessful, with so-called “killer” T-cells attacking the illness directly.
Antibody blood tests, which look at proteins to detect whether the body has tried to fight off the virus, are one way of seeing whether a person has had Covid-19 in the past.
But, according to a new report, some coronavirus patients who have had Covid-19 mildly have not had an antibody response, but do “show strong, specific T-cell immunity”.
Rosemary Boyton and Daniel Altmann, professors of immunology at Imperial College London, said: “If, as appears the case, measuring T-cell immunity is a more enduring and reliable marker of adaptive immunity in COVID-19 than antibody, it will be valuable to achieve rollout for health services of commercial T-cell testing kits.”
In their study Sars-CoV-2 T cell immunity: Specificity, function, durability, and role in protection – published in Science Immunology – the professors say a “basic observation in the majority of infected people…is one of robust T-cell activation”, and that widespread T-cell testing will be “valuable in deciphering” the development of Covid-19 as we “enter the next part of the battle”.
They added: “At the start of the pandemic, a key mantra was that we needed the game-changer of antibody data to understand who had been infected and how many were protected.
“As we have learnt more about this challenging infection, it’s time to admit that we really need the T cell data too.”
More than one million people in health and social care in the UK have had an antibody test, according to Baroness Dido Harding, head of the NHS Test and Trace scheme, but she said more work needs to be done before antibody testing can be more widely rolled out.
She told Friday’s Downing Street briefing: “At this stage the science isn’t clear enough yet to tell us whether the presence of antibodies and the level of antibodies in your blood gives you immunity.”
A vaccine currently under development by Oxford University is thought to have triggered a T-cell response as well as an antibody in some test subjects, according to reports.
More than 4,000 participants are already enrolled in the UK in the testing of the ChAdOx1 nCoV-19 vaccine, with enrolment of a further 10,000 people planned for the future.
This trial aims to assess how well people across a broad range of ages could be protected from Covid-19.
It will also provide valuable information on safety aspects of the vaccine and its ability to generate good immune responses against the virus.