Extracorporeal Photopheresis as a Possible Therapeutic Approach to Adults With Severe and Critical COVID-19

ECP is initiated on study inclusion day by Therakos Cellex system, according to manufacturers' instructions. Each patient receives two ECP cycles for 2 weeks, each consisting of two sessions on consecutive days per week (alltogether four sessions), through a peripheral or central venous route. Cycles 1 and 2 are separated by 5 consecutive days. One ECP session takes \~3 hours, and is separated into 4 phases. On priming, the system performes a series of calibrations to ensure proper operation. During collection, 1500 ml of whole blood is processed to collect a concentrated buffy coat containing white blood cells, while other cells and plasma are reinfused. During the photoactive phase, a prescribed dose of 8-methoxypsoralen is added to the buffy coat, which is then circulated through ultraviolet-A photoactivation. During reinfusion phase, treated cells are automatically reinfused to the patient.