1. Department of Industrial Engineering and Management, Ben-Gurion University of the Negev, P. O. 653, Beer-Sheva 84105, Israel.
2. Central Virology Laboratory, Ministry of Health, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel.
3. Biostatistics Unit, Gertner Institute for Epidemiology and Health Policy Research, Tel Hashomer 52621, Israel.
4. Public Health Services, Ministry of Health, Jerusalem 9101002, Israel.
5. Department of Public Health, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
6. School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, P. O. 39040, Tel Aviv 6997801, Israel.