Treating critically ill COVID-19 patients with corticosteroid drugs reduces the risk of death by 20%, an analysis of seven international trials found on Wednesday, prompting the World Health Organisation to update its advice on treatment. The analysis - which pooled data from separate trials of low dose hydrocortisone, dexamethasone and methylprednisolone - found that steroids improve survival rates of COVID-19 patients sick enough to be in intensive care in hospital.