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Background The 2017–2018 influenza season in Israel was characterized by the predominance of influenza B Yamagata, with a lesser circulation of influenza A(H1N1)pdm09 and influenza A(H3N2). We estimated vaccine effectiveness (VE) of the inactivated influenza vaccine which was selected for use that season. Methods End-of-season VE and 95% confidence intervals (CI) against laboratory-confirmed influenza-like illness (ILI) were estimated by means of the test-negative design. Age-specific VE analysis was carried out using a moving age interval. Results Specimen were obtained from 1,453 community ILI patients; 610 (42.0%) were influenza-positive, among which 69.7% were B, 17.2% A(H1N1)pdm09 and 13.4% A(H3N2). A 98.6% of molecularly characterized influenza B belonged to the Yamagata lineage. Of the sampled individuals, 1320 were suitable for VE analysis. Of those vaccinated, 90.6% received the inactivated trivalent influenza vaccine (TIV) containing a Victoria lineage influenza B-like virus. VE against influenza A differed by age, with the highest VE of 72.9% (95%CI 31.9–89.2%) observed in children 0.5–14 years old, while all ages VE was 46.6% (95%CI 10.4–68.2%). All ages VE against influenza B was 23.2% (95%CI −10.1–46.4%) with age-specific analysis showing non-significant VE estimates. Utilizing a moving age interval of 15 years, afforded a detailed age-specific insight into influenza VE against the influenza viruses circulating during the 2017–2018 season. Conclusions The moderate-high 2017–2018 influenza A VE among children and adolescents, supports seasonal influenza vaccination at a young age. The low VE against influenza B in Israel, is most likely the result of influenza B/TIV-mismatch.

Background The 2016-2017 influenza season in Israel was dominated by the circulation of influenza A(H3N2). Influenza vaccine is recommended for the entire population in Israel aged >6 months. The inactivated influenza vaccine was chosen for use this season. Methods We estimated the 2016-2017 end-of-season influenza vaccine effectiveness (VE) in preventing influenza-like illness due to influenza A(H3N2), using the test-negative design. Age-specific VE was estimated using a moving age window and weekly analysis. Results During the 2016-2017 season, 1267 samples were collected; 467 (36.9%) were positive for influenza, with 97.9% A(H3N2), 0.2% A(H1N1)pdm09, and 1.9% B. A total of 1088 individuals were found eligible to be included in VE assessment. All vaccinated individuals included in the VE assessment received the inactivated influenza vaccine. Adjusted VE against influenza A(H3N2) was 29.0% (95% confidence interval [CI], 0.3%-49.5%). Age group-specific adjusted VE was 69.2% (95% CI, 19.4%-88.3%) for children aged 5-17 years and 58.8% (95% CI, .8%-82.9%) for adults aged 45-64 years. Other age groups demonstrated lower VE estimates that were not statistically significant. Adjusted VE estimates using a moving window of 15 years and weekly VE analyses provided a more defined understanding of age-specific VE during the 2016-2017 season. Conclusions Estimating VE using a moving age window as well as weekly VE analysis may provide more detailed information regarding the relationship between VE and age.

BACKGROUND Influenza-related morbidity impacts healthcare systems, including hospitals. OBJECTIVE To obtain a quantitative assessment of hospitalization burden in pediatric and internal medicine departments during influenza seasons compared with the summer months in Israel. METHODS Data on pediatric and internal medicine hospitalized patients in general hospitals in Israel during the influenza seasons between 2005 and 2013 were analyzed for rate of hospitalizations, rate of hospitalization days, hospital length of stay (LOS), and bed occupancy and compared with the summer months. Data were analyzed for hospitalizations for all diagnoses, diagnoses of respiratory or cardiovascular disease (ICD9 390-519), and influenza or pneumonia (ICD9480-487), with data stratified by age. The 2009-2010 pandemic influenza season was excluded. RESULTS Rates of monthly hospitalizations and hospitalization days for all diagnoses were 4.8% and 8% higher, respectively, during influenza seasons as compared with the summers. The mean LOS per hospitalization for all diagnoses demonstrated a small increase during influenza seasons as compared with summer seasons. The excess hospitalizations and hospitalization days were especially noticed for the age groups under 1 year, 1-4 years, and 85 years and older. The differences were severalfold higher for patients with a diagnosis of respiratory or cardiovascular disease and influenza or pneumonia. Bed occupancy was higher during influenza seasons compared with the summer, particularly in pediatric departments. CONCLUSIONS Hospital burden in pediatric and internal medicine departments during influenza seasons in Israel was associated with age and diagnosis. These results are important for optimal preparedness for influenza seasons.

Background Influenza A and B viruses co-infections are rare events and mainly occurred in immunocompromised patients. Objectives In this study we report an unusually high occurrence of influenza A (H1N1)pdm 2009 and influenza B virus co-infections during the epidemic year 2015–2016. Study design Nasopharyngeal swabs were collected from 1919 patients visiting 26 outpatient clinics distributed throughout Israel and presenting with influenza-like illness. In addition, hospitalized patient tested for influenza viruses were also included in the study. Patients samples collected between October 2015 and April 2016 were tested for the presence of influenza viruses by real-time PCR. Results Of the 1919 patient samples tested, 11 (0.6%) were co-infected with both influenza A(H1N1)pdm 2009 and influenza B/Victoria viruses. Similar observation was noted in four hospitalized patients during the same period. Patients at ages 1–72 years, and their clinical symptoms were similar to that of patients infected with either influenza A or B viruses. Of all patients, only one hospitalized patient was immunocompromised. In conclusion : Co-infection of influenza A(H1N1)pdm 2009 and influenza B viruses is an increasingly recognized phenomenon. This co-infection can occur not only in immunocompromised individuals, but also in immunocompetent patients. Although co-infection appears to be a rare event, it may still play a role in the epidemiology, pathogenicity and evolution of 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.

The seasonal influenza vaccine is currently the most effective preventive modality against influenza infection. Nasopharyngeal samples of vaccinated and non-vaccinated patients presenting with Influenza-like-illness (ILI) were collected from over 20 outpatient clinics located in different geographic parts of Israel and were tested for the presence of influenza viruses (influenza A and influenza B). Here we show, that in the 2014-2015 season, the vaccine that included the A/Texas/50/2012 H3N2 virus was ineffective. Significant numbers of individuals vaccinated with the 2014-2015 vaccine, of all ages, were infected with influenza A (H3N2), manifesting similar symptoms as the non-vaccinated group. We further demonstrate that the Israeli circulating influenza A(H3N2) virus was different than that included in the 2014-2015 northern hemisphere vaccine, and that antibodies elicited by this vaccine were significantly less efficient in neutralizing influenza A(H3N2) infection.

BACKGROUND Increased upper respiratory infection (URI) among children at the beginning of school year is well known to parents and pediatricians. However, this phenomenon is not well documented or characterized. METHODS Computerized datasets from a large health maintenance organization in Israel were used to calculate the weekly rates of URI among children 3-14 years old for the years 2007-2012. In addition, nasopharyngeal swabs were collected in 2010-2012 from children with URI symptoms and controls during school opening time. Swabs were tested by real-time polymerase chain reaction for the presence of respiratory viruses. RESULTS Time-series analysis demonstrated a peak of URI in September each year. The peaks reached their height 2 weeks after school opening and returned to baseline within 4-7 weeks. The main 3 viruses detected both in URI patients and in healthy controls during the first weeks of school opening were rhinovirus, adenovirus and enterovirus. The detection rate of any respiratory virus, and of rhinovirus in particular, was significantly higher among cases than among controls (54% vs. 16%, P < 0.001 for any virus, and 35% vs. 6.0%, P < 0.01 for rhinovirus). When adjusting for age and sex cases had 5.8 times more viral detection when compared with controls. Upper respiratory symptoms were significantly more prevalent among the virus-positive cases when compared with negative ones. CONCLUSIONS Back-to-school illness consisting of URI has a distinct epidemiological pattern demonstrating a rapid rise peaking within 2 weeks of school opening and is associated predominantly with rhinovirus.

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.