1. Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel
2. Department of Pediatrics, Hillel Yaffe Medical Center, Hadera, Israel
3. Department of Pediatrics, Laniado Medical Center, Netanya, Israel
4. Department of Pediatrics, Carmel Medical Center, Haifa, Israel
5. Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
6. Central Virology Laboratory, Ministry of Health, Tel Hashomer, Israel