Using blood plasma from COVID-19 survivors to treat patients with severe pneumonia caused by the novel coronavirus has little benefit, according to data from a clinical trial in Argentina.

The therapy know as convalescent plasma, which delivers antibodies from COVID-19 patients to infected people, did not significantly improve patients’ health status or reduce their risk of dying from the disease any better than a placebo, the study shows

Despite limited evidence of its efficacy, convalescent plasma, which US President Donald Trump touted in August as a “historic breakthrough”, has been frequently given to patients in the US.

In October, a small study from India suggested convalescent plasma improved symptoms in COVID-19 patients, such as shortness of breath and fatigue, but did not reduce the risk of death or progression to severe disease after 28 days