Scientists at Britain's Oxford University have started a clinical trial to investigate the effects of an HIV medicine and a steroid drug in UK patients admitted to hospital with Covid-19 caused by the new coronavirus, Reuters reports.

The first patients have already been enrolled for the trial within the country's National Health Service, the researchers said on Monday.

It will test AbbVie's Kaletra — a combination of lopinavir and ritonavir which is normally used to treat the Human Immunodeficiency Virus (HIV) that causes AIDS — and the steroid dexamethasone, which is used to reduce inflammation in a wide range of conditions.

The researchers stressed that while it was possible some existing drugs such as these may be beneficial in the fight against Covid-19, there was no guarantee they would be.