A National Collaborative Multicenter Phase II Study for Potential Efficacy of Convalescent Plasma to Treat Severe COVID-19 and Patients at High Risk of Developing Severe COVID-19

King Fahad Specialist Hospital (Dammam), International Medical Center (Jeddah), King Abdulaziz Medical City NG (Riyadh), King Abdulaziz Medical City NG (Jeddah), King Abdulaziz Hospital NG (Al Ahsa), Prince Mohammad bin Abdulaziz Hospital NG (Medina), Qatif Central Hospital, Dammam Medical Complex, King Fahad Medical City (Riyadh), King Saud Medical City (Riyadh), King Abdullah Medical City (Makkah), Al-Noor Specialist Hospital (Makkah), King Abdullah Medical Complex (Jeddah), Ohud hospital (Medina), King Fahad Genaral Hospital (Medina), Aseer Central Hospital (Abha)