South Korean drugmaker Celltrion Inc has announced positive results for its experimental antibody Covid-19 treatment that it said was safe and reduced the treatment period by nearly five days in Phase 3 global clinical trials.

The trials, which involved 1,315 participants, have taken place since January in 13 countries, including in South Korea, the United States, Spain and Romania, Celltrion said in a statement.

The treatment slowed severe symptoms of Covid-19 in more than 70 per cent of patients, including the high risk group with underlying conditions. It also cut the recovery period by 4.9 days, the company said.