“The virus seems to be causing increased clotting in the large arteries, leading to severe stroke,” Oxley told CNN.

“Our report shows a seven-fold increase in incidence of sudden stroke in young patients during the past two weeks. Most of these patients have no past medical history and were at home with either mild symptoms (or in two cases, no symptoms) of Covid,” he added…

It is not common for people so young to have strokes, especially strokes in the large vessels in the brain.

“For comparison, our service, over the previous 12 months, has treated on average 0.73 patients every 2 weeks under the age of 50 years with large vessel stroke,” the team wrote in a letter to be published in the New England Journal of Medicine. That’s fewer than two people a month.