Additional reports of patients with long Covid who were helped by Pfizer Inc's oral antiviral treatment Paxlovid offer fresh impetus for conducting clinical trials to test the medicine for the debilitating condition, US researchers said on Thursday.

Three new case studies follow earlier reports of long Covid patients who experienced relief of their symptoms after taking the treatment, which is currently only authorised for high-risk people early after onset of Covid-19 symptoms.

As many as 30 percent of people infected by the coronavirus are...