Austrian Association for Quality Assurance and Standardization of Medical and Diagnostic Tests (ÖQUASTA), University Hospitals Birmingham NHS Foundation Trust, UK National External Quality Assessment Scheme (UK NEQAS) for Haematology, Centre Toulousain pour le Contrôle de qualité en Biologie clinique (CTCB), EQALM Virtual Microscopy Working Group, Royal College of Pathologists of Australasia Quality Assurance Program, Labquality, Independent, Leiden University Medical Centre, Sciensano, Laboratoire National de Métrologie et d’Essais (LNE), Reference Institute for Bioanalytics, Medical University of Innsbruck - University Hospital of Innsbruck, Rigshospitalet Glostrup, LGC, Ltd., University of Szeged, University of Szeged, Technische Universität München (TUM), External Quality Control for Assays and Tests (ECAT) Foundation, Labquality, Careggi University Hospital of Florence, The Norwegian Organization for Quality Improvement of Laboratory Examinations (Noklus), INSTAND e.V. Society for Promoting Quality Assurance in Medical Laboratories, Radboud University - Radboud University Medical Center, Institut für Qualitätssicherung in der Virusdiagnostik - IQVD GmbH, University of British Columbia (UBC) - Department of Pathology and Laboratory Medicine and University of British Columbia (UBC) - Department of Pathology and Laboratory Medicine