1 Department of Medicine, King Abdulaziz Medical City, Riyadh 11426, Saudi Arabia; College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; King Abdullah International Medical Research Center, Riyadh, Saudi Arabia. Electronic address: bosaeedmo@ngha.med.sa.
2 Gulf Center for Disease Prevention and Control, Riyadh, Saudi Arabia.