Doctors at University College Hospital will investigate whether it can improve their chances of survival and reduce the time spent in hospital by reducing inflammation in the lungs.
It could also enable patients to take the drug at home — either leading to earlier discharge from hospital or possibly avoiding admission at all.
The trial, being run by University College London and the Francis Crick Institute, will involve up to 40 patients with mild Covid receiving the drug Dornase alfa, with the first being recruited within days. It will not include patients on ventilation.
Researchers believe the immune system in Covid-19 patients is over-active and could be causing excess inflammation and contributing to the onset of pneumonia and severe damage to the lungs.
Patients will be given the drug twice a day for a week and their outcomes compared against an existing database of 120 patients previously treated for Covid at UCH.
Professor Joanna Porter, the chief clinical investigator and a consultant in respiratory and general medicine at UCLH, said: “Hyperinflammation is an overreaction of the body’s immune system, which can cause serious breathing problems and has proven to be one of the most fatal conditions in those with severe Covid-19.
“Dornase alfa has an excellent safety profile and has been used for many decades to help break down mucus secretion in the lungs of patients with cystic fibrosis.” The trial is based on research by Dr Venizelos Papayannopoulos at the Crick. Cystic fibrosis is an inherited condition that causes mucus to build up in the lungs.