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Background: Influenza A (H3N2) clade 3C.3a was the predominant influenza virus in Israel throughout the 2018-2019 season, constituting a drift from the influenza A (H3N2) vaccine. We estimated the end-of season vaccine effectiveness (VE) by age, among community patients with influenza-like illness (ILI), considering the hemagglutinin (HA) gene mutations and amino acid substitutions of influenza A (H3N2) viruses detected. Methods: Nose-throat samples were analyzed for the presence of influenza virus, type/subtype, and HA gene sequence. HA gene sequences and amino acid substitutions were compared to the influenza A/Singapore/INFIMH-16-0019/2016 (H3N2)-like 2018-2019 vaccine virus, and a phylogenetic tree was generated. Influenza VE against influenza A (H3N2) was estimated using the test-negative design. VE was estimated by age group and by 15 year moving age intervals. Results: In total, 90% of the influenza A (H3N2) viruses belonged to the 3C.3a clade, constituting a unique situation in the northern hemisphere. Adjusted all-age influenza A (H3N2) VE was −3.5% (95% CI: −51.2 to 29.1). Although adjusted VEs were very low among infants, children, and young adults, a VE of 45% (95% CI: −19.2 to 74.6) was estimated among adults aged ≥45 years old. Conclusions: The higher VE point estimates among older adults may be related to previous exposure to similar influenza viruses.

// Nehemya Friedman 1, 2, * , Yaron Drori 1, 2, * , Rakefet Pando 3 , Aharona Glatman-Freedman 3, 4 , Hanna Sefty 3 , Ravit Bassal 3 , Yaniv Stein 3 , Tamy Shohat 2, 3 , Ella Mendelson 1, 2 , Musa Hindiyeh 1, 2 , Michal Mandelboim 1, 2 1 Central Virology Laboratory, Ministry of Health, Chaim Sheba Medical Center, Ramat-Gan, Israel 2 Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel 3 The Israel Center for Disease Control, Israel Ministry of Health, Tel-Hashomer, Israel 4 Departments of Pediatrics and Family and Community Medicine, Valhalla, New York, USA * These authors contributed equally to this work Correspondence to: Michal Mandelboim, email: michalman@sheba.health.gov.il Keywords: influenza A, H1N1, vaccine, Clade 6B Received: November 22, 2016 Accepted: March 14, 2017 Published: March 22, 2017 ABSTRACT The last influenza pandemic, caused by the swine A(H1N1)pdm09 influenza virus, began in North America at 2009. Since then, the World Health Organization (WHO) recommended integration of the swine-based virus A/California/07/2009 strain in yearly vaccinations. Yet, infections with A(H1N1)pdm09 have continued in subsequent years. The reasons for this are currently unknown. During the 2015–2016 influenza season, we noted an increased prevalence of A(H1N1)pdm09 influenza virus infection in Israel. Our phylogenetic analysis indicated that the circulating A(H1N1)pdm09 strains belonged to 6B.1 and 6B.2 clades and differed from the vaccinating strain, with approximately 18 amino acid differences found between the circulating strains and the immunizing A/California/07/2009 strain. Hemmaglutination inhibition (HI) assays demonstrated higher antibodies titer against the A/California/07/2009 vaccinating strain as compared to the circulating Israeli strains. We thus suggest that the current vaccination was not sufficiently effective and propose inclusion of the current circulating A(H1N1)pdm09 influenza viruses in the annual vaccine composition.

Introduction Influenza vaccine is recommended for the entire population in Israel. We assessed influenza vaccine effectiveness (VE) for the 2014/15 and 2015/16 seasons in Israel, for the first time. Methods: Combined nose and throat swab specimens were collected from patients with influenza-like illness (ILI) presenting to sentinel primary care clinics and tested for influenza virus by RT-PCR. VE of the trivalent inactivated vaccine (TIV) was assessed using test-negative case–control design. Results: During the 2014/15 season 1,142 samples were collected; 327 (28.6%) were positive for influenza, 83.8% A(H3N2), 5.8% A(H1N1)pdm09, 9.2% B and 1.2% A un-subtyped. Adjusted VE against all influenza viruses for this influenza season was −4.8% (95% confidence interval (CI): −54.8 to 29.0) and against influenza A(H3N2), it was −15.8% (95% CI: −72.8 to 22.4). For the 2015/16 season, 1,919 samples were collected; 853 (44.4%) were positive for influenza, 43.5% A(H1N1)pdm09, 57% B, 0.7% A(H3N2) and 11 samples positive for both A(H1N1)pdm09 and B. Adjusted VE against all influenza viruses for this influenza season was 8.8% (95% CI: −25.1 to 33.5), against influenza A(H1N1)pdm09, it was 32.3% (95% CI: (−4.3 to 56.1) and against influenza B, it was −2.2% (95% CI: (−47.0 to 29.0). Conclusions: Using samples from patients with ILI visiting sentinel clinics in Israel, we demonstrated the feasibility of influenza VE estimation in Israel.

Background The crude rate of early-onset Group B streptococcus disease (EOGBS) in Israel has been consistently under 0.5 for 1000 live births for the past 8 years. The Israeli Ministry of Health has adapted the risk factor based approach for preventing EOGBS and universal bacteriological screening for GBS is not recommended. In spite of this policy, there are indications that many pregnant women in Israel undergo bacteriological screening for GBS. The objective of this study is to assess the rate and characteristics of pregnant women who undergo screening for group B streptococcus (GBS) colonization in Israel. Methods Survey of expectant mothers who came to give birth in 29 delivery rooms throughout Israel during the month of July 2012 regarding GBS screening practice and demographics. Results A total of 2968 pregnant women participated in the assessment. Among them, 935 women (31.5 %) had been tested for GBS colonization. About 90 % of those women had no risk factors, only 542 women (60 %) underwent testing during the recommended gestational timing (35–37 weeks) and 23 % of the tested women reported being GBS carriers. GBS screening as part of the routine pregnancy follow- up was associated with: residence district, intermediate or high socioeconomic rank, being a member of certain health maintenance organization and being Jewish. Characteristics found to be significantly associated with being a GBS carrier were: low socioeconomic rank, and having a risk factor for GBS infection. Conclusions A substantial number of pregnant women in Israel undergo screening for GBS colonization despite the national policy against universal screening. While GBS colonization was more prevalent in women of lower socioeconomic status, screening is done more often in those of higher socioeconomic status, suggesting unnecessary monetary expenses.