1. (former) Department of Virology, National Centre of Infectious and Parasitic Diseases, Sofia, Bulgaria
2. University of Ljubljana, Faculty of Medicine, Institute of Microbiology and Immunology, Ljubljana, Slovenia
3. Blood Transfusion Centre of Slovenia, Ljubljana, Slovenia
4. Division of Virology, National Institute of Cholera and Enteric Diseases, Kolkata, India
5. Infectious Ward, University Hospital ‘St Anna’, Sofia, Bulgaria
6. Infectious Wards 1 and 2, Specialized Hospital for Infectious and Parasitic Diseases ‘Prof. Ivan Kirov’, Sofia, Bulgaria
7. Institute of Infection and Global Health, University of Liverpool, Liverpool, UK