UK scientists are to begin testing a treatment that it is hoped could counter the effects of Covid-19 in the most seriously ill patients.
It has been found those with the most severe form of the disease have extremely low numbers of an immune cell called a T-cell.
T-cells clear infection from the body.
The clinical trial will evaluate if a drug called interleukin 7, known to boost T-cell numbers, can aid patients’ recovery.
It involves scientists from the Francis Crick Institute, King’s College London and Guy’s and St Thomas’ Hospital.
They have looked at immune cells in the blood of 60 Covid-19 patients and found an apparent crash in the numbers of T-cells.
Prof Adrian Hayday from the Crick Institute said it was a “great surprise” to see what was happening with the immune cells.
“They’re trying to protect us, but the virus seems to be doing something that’s pulling the rug from under them, because their numbers have declined dramatically.
In a microlitre (0.001ml) drop of blood, normal healthy adults have between 2,000 and 4,000 T-cells, also called T lymphocytes.
The Covid patients the team tested had between 200-1,200.
The researchers say these findings pave the way for them to develop a “fingerprint test” to check the levels of T-cells in the blood which could provide early indications of who might go on to develop more severe disease.
But it also provides the possibility for a specific tre