EPIDEMIOLOGICAL AND VIROLOGICAL CHARACTERIZATION OF INFLUENZA VIRUS B DETECTED IN PATIENTS FROM ISRAEL

Sivan Sharabi ¹ Musa Hindiyeh ^1,2 Michal Michaeli ¹ Sara Orzitzer ¹ Aharona Glatman-Freedman ³ Tamy Shohat ^2,3 Ella Mendelson ^1,2 Michal Mandelboim ¹

¹Central Virology Laboratory, Ministry of Health, Sheba Medical Center, Ramat-Gan, Israel
²Department of Epidemiology and Preventive Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
³The Israel Center for Disease Control, Israel Ministry of Health, Tel-Hashomer, Israel

While influenza A viruses comprise a large group of clinically relevant influenza viruses, influenza B viruses form a more homogeneous group, which are categorized mainly into the Victoria and Yamagata lineages. The divergence of influenza B viruses into two main lineages has complicated seasonal influenza vaccine design, which traditionally contained two seasonal influenza A strains and one influenza B strain. Thus, it is important to understand whether both influenza B lineages should be included in the vaccine or whether one is sufficient. Here, we examined the distribution of the two influenza B lineages in Israel between 2011-2014, in both hospitalized and non-hospitalized influenza B infected patients. Our results demonstrated that influenza B infections can lead to hospitalization and show that in some winter seasons, both B lineages circulated simultaneously in Israel. Interestingly, we found that while the Victoria lineage affected mostly young people below the age of 30, elderly people were particularly vulnerable to Yamagata infections.

Our results supports the importance of including the two main influenza virus B lineages in the influenza vaccine cocktail.