(Reuters) - Drugs used for treating arthritis are being tested as treatments for COVID-19, the disease caused by a new coronavirus, as researchers rush to find ways of helping patients and slowing the number of infections.

FILE PHOTO: A Sanofi sign outside the French drugmaker's Paris headquarters, October 30, 2014. REUTERS/Christian Hartmann//File Photo

Sanofi and Regeneron Pharmaceuticals said on Monday they began a clinical trial of their rheumatoid arthritis drug Kevzara as a coronavirus treatment, while in Spain a separate trial is studying if a combination of two drugs can slow down the spread of coronavirus among people.

Enrolments for the mid-to-late stage trial of Kevzara, an immune-system modifying drug known as a monoclonal antibody, will begin immediately and test up to 400 patients, Sanofi and Regeneron said in a joint statement.

Regeneron in February announced a partnership with the U.S. Department of Health and Human Services to develop a treatment for the new coronavirus, called SARS-CoV2, and said it would focus on monoclonal antibodies.

The virus that emerged in central China in December has now infected more than 179,000 people worldwide, according to the Johns Hopkins University, which is tracking these figures.

Doctors have seen that many of those who become critically ill from SARS-CoV2 are experiencing a so-called cytokine storm, which happens when the immune system overreacts and attacks the body’s organs. Some researchers think drugs that can suppress the immune system, including monoclonal antibodies, might be useful for limiting this autoimmune response.

Meanwhile, Barcelona-based researchers said on Monday they would administer a drug used to treat HIV - containing darunavir and cobicistat - to a coronavirus-infected person.

The patient’s close contacts would be administered hydroxychloroquine, a drug for malaria and rheumatoid conditions because laboratory experiments suggest it prevents this strain of coronavirus from reproducing.

“The goal of our study is to separate the transmission chains,” Oriol Mitja, researcher at Germans Trias i Pujol Research Institute, told a news briefing.

Patients with coronavirus can infect between 5% and 15% of the people they come into contact with during the 14 days after starting to show symptoms, he said.

The trial’s goal is to reduce that number below 14 days and also to reduce the percentage of contacts infected and researchers plan to analyze the results in 21 days.

Around 200 patients with coronavirus and 3,000 of their close contacts will take part in the trial, which has private and public funding.

Mitja - who plans to talk with World Health Organization officials this week - said there were two other similar projects in Australia and the United States, but that his is in the lead.

Also on Monday, Madrid’s La Paz-Carlos III hospital announced a trial to administer another antiviral drug, Remdesivir, to voluntary patients with serious and milder cases of coronavirus, Madrid’s regional government said in a statement.

About 1,000 patients will take part in the European-wide trial, it said.