High levels of so-called "T cells" that respond to the coronavirus could be sufficient to offer protection against infection, an English study said on Tuesday, adding to the evidence of the crucial role they play in immunity to COVID-19.
T cells, a type of white blood cell that makes up part of a healthy immune system, are thought to be essential to protect against infection from the SARS-COV-2 coronavirus, and could provide longer term immunity than antibodies.
The study on nearly 3,000 people, conducted by Oxford Immunotec and Public Health England (PHE), found that no participants with a high T cell response developed symptomatic SARS-CoV-2 infection when researchers followed up with them.
That compares to 20 confirmed infections among participants who saw low T cell responses.
"This suggests individuals with higher numbers of T-cells recognising SARS-CoV-2 may have some level of protection from COVID-19, although more research is required to confirm this," said David Wyllie, Consultant Microbiologist at Public Health England.
The study was a pre-print, and has not been published in a journal or peer reviewed.
The researchers suggested that the importance of T cells in the immune response might mean serological testing to detect antibodies would not paint a full picture of who was at lower risk of infection in the population.
They also said that levels of SARS-CoV-2 responsive T cells declined with age, especially in the absence of antibodies, possibly explaining why older people are more at risk from COVID-19.
Oxford Immunotec, which has a platform designed to measure T cell response, has been enlisted by Britain to provide testing to assess different coronavirus vaccine candidates.
(Reporting by Alistair Smout; Editing by Jan Harvey)
