1. Central Virology Laboratory, Ministry of Health, Sheba Medical Center, Ramat Gan;
2. Tel-Aviv District Health Office, Ministry of Health, Tel Aviv, Israel;
3. Public Health Services, Ministry of Health, Jerusalem, Israel;
4. Hebrew University Hadassah Braun School of Public Health and Community Medicine, Jerusalem
5. Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva, Israel;
6. School of Public Health, Tel Aviv University, Tel Aviv