A nurse controls the heart beat of a patient who recovered from COVID-19 during a 6 minutes of self-paced walking test, in a former COVID-19 patient rehabilitation center inside the field hospital in Crema, southeast of Milan, on May 15, 2020 during the country's lockdown aimed at curbing the spread of the COVID-19 infection, caused by the novel coronavirus. (Photo by MIGUEL MEDINA / AFP) (Photo by MIGUEL MEDINA/AFP via Getty Images)