Ten influenza seasons in France: distribution and timing of influenza A and B circulation, 2003-2013

Differential interferon responses to influenza A and B viruses in primary ferret respiratory epithelial cells

Influenza B viruses (IBV) cocirculate with influenza A viruses (IAV) and cause periodic epidemics of disease, yet antibody and cellular responses following IBV infection are less well understood. Using the ferret model for antisera generation for influenza surveillance purposes, IAV resulted in robust antibody responses following infection, whereas IBV required an additional booster dose, over 85% of the time, to generate equivalent antibody titers. In this study, we utilized primary differentiated ferret nasal epithelial cells (FNECs) which were inoculated with IAV and IBV to study differences in innate immune responses which may result in differences in adaptive immune responses in the host. FNECs were inoculated with IAV (H1N1pdm09 and H3N2 subtypes) or IBV (B/Victoria and B/Yamagata lineages) and assessed for 72 h. Cells were analyzed for gene expression by quantitative real-time PCR, and apical and basolateral supernatants were assessed for virus kinetics and interferon (IFN), respectively. Similar virus kinetics were observed with IAV and IBV in FNECs. A comparison of gene expression and protein secretion profiles demonstrated that IBV-inoculated FNEC expressed delayed type-I/II IFN responses and reduced type-III IFN secretion compared to IAV-inoculated cells. Concurrently, gene expression of Thymic Stromal Lymphopoietin (TSLP), a type-III IFN-induced gene that enhances adaptive immune responses, was significantly downregulated in IBV-inoculated FNECs. Significant differences in other proinflammatory and adaptive genes were suppressed and delayed following IBV inoculation. Following IBV infection, ex vivo cell cultures derived from the ferret upper respiratory tract exhibited reduced and delayed innate responses which may contribute to reduced antibody responses in vivo.IMPORTANCEInfluenza B viruses (IBV) represent nearly one-quarter of all human influenza cases and are responsible for significant clinical and socioeconomic impacts but do not pose the same pandemic risks as influenza A viruses (IAV) and have thus received much less attention. IBV accounts for greater severity and deaths in children, and vaccine efficacy remains low. The ferret can be readily infected with human clinical isolates and demonstrates a similar course of disease and immune responses. IBV, however, generates lower antibodies in ferrets than IAV following the challenge. To determine whether differences in initial innate responses following infection may affect the development of robust adaptive immune responses, ferret respiratory tract cells were isolated, infected with IAV/IBV, and compared. Understanding the differences in the initial innate immune responses to IAV and IBV may be important in the development of more effective vaccines and interventions to generate more robust protective immune responses.

Differentiation of influenza B lineages circulating in different regions of Brazil, 2014 – 2016, using molecular assay

Background

Two antigenically and genetically distinct lineages of influenza B viruses (B/Victoria and B/Yamagata) have been co-circulating worldwide since 2002. Virological surveillance is essential to differentiate between both lineages with a view to the annual updating of the B component for the trivalent or quadrivalent influenza vaccine composition.

Methods

The samples analyzed in the present study were collected by influenza sentinel units located in the Southeast, Midwest, North, and Northeast regions of Brazil, part of the National Influenza Virus Surveillance Network, coordinated by the Ministry of Health of Brazil. A total of 870 influenza B positive samples by reverse transcription real – time polymerase chain reaction (RT-qPCR), collected during 2014, 2015, and 2016 influenza seasons, were submitted to the influenza B lineage genotyping panel for characterization as B/Yamagata or Victoria lineages using RT-qPCR.

Results

Of the 197 samples analyzed in 2014, a total of 160 (81 %) corresponded to the B/Yamagata lineage, 19 (10 %) to the B/Victoria lineage, and 18 (9 %) to indeterminate lineages. Of the 190 samples analyzed in 2015, a total of 124 (65 %) corresponded to the B/Yamagata lineage; 55 (29 %) to the B/Victoria lineage, whereas 11 (6 %) were of indeterminate lineages. Of the 483 samples analyzed in 2016, a total of 297 (62 %) corresponded to the B /Victoria lineage; 174 (36 %) to the B/Yamagata lineage and 12 (2 %) to indeterminate lineages. This cross-sectional study revealed influenza B virus (IBV) infection in all age groups, and among them, the highest prevalence was observed in individuals between 11 and 49 years of age Our findings demonstrate the match between influenza B virus lineages recommended by the World Health Organization (WHO) for the trivalent vaccine composition to be used in the Southern Hemisphere (SH) and the predominant circulating viruses during the 2014, 2015, and 2016 seasons.

Epidemiological survey to establish thresholds for influenza among children in satellite cities of Tokyo, Japan, 2014-2018

OBJECTIVE

We described the characteristics of children reported as having influenza across five consecutive influenza seasons and investigated the usefulness of setting influenza thresholds in two satellite cities of Tokyo, Japan.

METHODS

An annual survey was conducted among parents of children at preschools (kindergartens and nursery schools), elementary schools and junior high schools in Toda and Warabi cities, Saitama prefecture, at the end of the 2014-2018 influenza seasons. Using the World Health Organization method, we established seasonal, high and alert thresholds.

RESULTS

There were 64 586 children included in the analysis. Over the five seasons, between 19.1% and 22% of children annually were reported as having tested positive for influenza. Influenza type A was reported as the dominant type, although type B was also reported in more than 40% of cases in the 2015 and 2017 seasons. The median period of the seasonal peak was 3 weeks in mid-January, regardless of school level. Of the five surveyed seasons, the high threshold was reached in 2014 and 2018, with no season exceeding the alert threshold.

DISCUSSION

This study provides insights into the circulation of influenza in children in the study areas of Toda and Warabi, Japan, from 2014 to 2018. Although we were able to utilize these annual surveys to calculate influenza thresholds from five consecutive seasons, the prospective usefulness of these thresholds is limited as the survey is conducted at the end of the influenza season.

Spotlight influenza: Laboratory-confirmed seasonal influenza in people with acute respiratory illness: a literature review and meta-analysis, WHO European Region, 2004 to 2017

Background

Across the World Health Organization European Region, there are few estimates of the proportion of people seeking medical care for influenza-like illness or acute respiratory infections and who have laboratory-confirmed seasonal influenza infection.

Methods

We conducted a meta-analysis of data extracted from studies published between 2004 and 2017 and from sentinel data from the European surveillance system (TESSy) between 2004 and 2018. We pooled within-season estimates by influenza type/subtype, setting (outpatient (OP)/inpatient (IP)) and age group to estimate the proportion of people tested who have laboratory-confirmed and medically-attended seasonal influenza in Europe.

Results

In the literature review, the pooled proportion for all influenza types was 33% (95% confidence interval (CI): 30–36), higher among OP 36% (95% CI: 33–40) than IP 24% (95% CI: 20–29). Pooled estimates for all influenza types by age group were: 0–17 years, 26% (22–31); 18–64 years, 41% (32–50); ≥ 65 years, 33% (27–40). From TESSy data, 33% (31–34) of OP and 24% (21–27) of IP were positive. The highest proportion of influenza A was in people aged 18–64 years (22%, 16–29). By subtype, A(H1N1)pdm09 was highest in 18–64 year-olds (16%, 11–21%) whereas A(H3N2) was highest in those ≥ 65 years (10%, 2–22). For influenza B, the highest proportion of infections was in those aged 18–64 years (15%, 9–24).

Conclusions

Laboratory-confirmed influenza accounted for approximately one third of all acute respiratory infections for which medical care was sought during the influenza season.

New 2013 incidence peak in childhood narcolepsy: more than vaccination?

Increased incidence rates of narcolepsy type-1 (NT1) have been reported worldwide after the 2009-2010 H1N1 influenza pandemic (pH1N1). While some European countries found an association between the NT1 incidence increase and the H1N1 vaccination Pandemrix, reports from Asian countries suggested the H1N1 virus itself to be linked to the increased NT1 incidence. Using robust data-driven modeling approaches, that is, locally estimated scatterplot smoothing methods, we analyzed the number of de novo NT1 cases (n = 508) in the last two decades using the European Narcolepsy Network database. We confirmed the peak of NT1 incidence in 2010, that is, 2.54-fold (95% confidence interval [CI]: [2.11, 3.19]) increase in NT1 onset following 2009-2010 pH1N1. This peak in 2010 was found in both childhood NT1 (2.75-fold increase, 95% CI: [1.95, 4.69]) and adulthood NT1 (2.43-fold increase, 95% CI: [2.05, 2.97]). In addition, we identified a new peak in 2013 that is age-specific for children/adolescents (i.e. 2.09-fold increase, 95% CI: [1.52, 3.32]). Most of these children/adolescents were HLA DQB1*06:02 positive and showed a subacute disease onset consistent with an immune-mediated type of narcolepsy. The new 2013 incidence peak is likely not related to Pandemrix as it was not used after 2010. Our results suggest that the increased NT1 incidence after 2009-2010 pH1N1 is not unique and our study provides an opportunity to develop new hypotheses, for example, considering other (influenza) viruses or epidemiological events to further investigate the pathophysiology of immune-mediated narcolepsy.

Vaccination of pregnant women against influenza: what is the optimal timing?

Pregnant women and young infants are at increased risk for severe influenza and its complications. Influenza vaccination during pregnancy is increasingly implemented as a strategy aiming to protect the pregnant woman, the fetus and the young infant. In clinical practice, the achievement of satisfactory protection for the pregnant woman without compromising the protection of her infant during the first months of life remains a challenge. Determinants that are implicated in the optimal timing of influenza vaccination in pregnancy include influenza season, trimester of pregnancy, maternal host factors and infant factors. This article addresses influenza vaccination in pregnancy and presents recent published evidence on issues that affect the optimization of the timing of maternal vaccination.

Estimation of influenza-attributable burden in primary care from season 2014/2015 to 2018/2019, France

Influenza viruses cause seasonal epidemics whose intensity varies according to the circulating virus type and subtype. We aim to estimate influenza-like illness (ILI) incidence attributable to influenza viruses in France from October 2014 to May 2019. Physicians participating in the French Sentinelles network reported the number of patients with ILI seen in consultation and performed nasopharyngeal swabs in a sample of these patients. The swabs were tested by RT-PCR for the presence of influenza viruses. These clinical and virological data were combined to estimate ILI incidence attributable to influenza viruses by subtypes and age groups. Influenza incidence rates over seasons ranged from 1.9 (95% CI, 1.9; 2.0) to 3.4% (95% CI, 3.2; 3.6) of the population. Each season, more than half of ILI cases were attributable to influenza. Children under 15 years were the most affected, with influenza incidence rates ranging from 3.0 (95% CI, 2.8;3.3) to 5.7% (95% CI, 5.3;6.1). Co-circulation of several (sub)types of influenza viruses was observed each year, except in 2016/2017 where A(H3N2) viruses accounted for 98.0% of the influenza cases. Weekly ILI incidences attributable to each influenza virus (sub)type were mostly synchronized with ILI incidence, except in 2014/2015 and 2017/2018, where incidence attributable to type B viruses peaked few weeks later. The burden of medically attended influenza among patients with ILI is significant in France, varying considerably across years and age groups. These results show the importance of influenza surveillance in primary care combining clinical and virological data.

Attitudes, knowledge, and willingness to be vaccinated against seasonal influenza among patients hospitalized with influenza-like-illness: impact of diagnostic testing

Influenza vaccine adherence remains low. Communication of virological diagnosis to adults hospitalized with influenza-like illness (ILI) could improve their willingness to be subsequently vaccinated. We prospectively assessed, in adults hospitalized with ILI in six French university hospitals, their willingness to be vaccinated against influenza in the subsequent season, both before and after the communication of RT-PCR Influenza laboratory result; we identified then the determinants associated with the willingness to be vaccinated.A total of 309 patients were included during the 2012-2013 and 2013-2014 influenza seasons; 43.8% reported being vaccinated against influenza for the current season; before communication of influenza laboratory results, 65.1% reported willingness to be vaccinated during the subsequent season. Influenza was virologically confirmed in 103 patients (33.3%). The rate of vaccine willingness increased to 70.4% (p = .02) after communication of influenza laboratory results. Factors independently associated with the willingness to be vaccinated were the perception of influenza vaccine benefits (adjusted relative risk (aRR): 1.06, 95%CI 1.02-1.10), cues to action (aRR: 1.08, 95%CI 1.03-1.12), current season influenza vaccination (aRR: 1.38, 95%CI 1.20-1.59) and communication of a positive influenza laboratory result (aRR: 1.18, 95%CI 1.03-1.34). This last was associated with the willingness to be vaccinated only in the subpopulation of patients not vaccinated (aRR: 1.53, 95%CI 1.19-1.96).In patients hospitalized with ILI, communication of a positive influenza diagnostic led to a better appreciation of the disease's severity and increased the willingness to be vaccinated. This approach might be particularly beneficial in patients who do not have a history of influenza vaccination.

Epidemiological and Immunological Features of Influenza Viruses in Hospitalized Children with Influenza Illness in Hangzhou

Objectives: We evaluated the epidemiological features and various inflammatory markers in hospitalized children with influenza virus infection in China. Methods: The real-time RT-PCR assay was performed for detection and genotyping of influenza A and B virus. Th1/Th2 cytokines, WBC, and CRP were determined in influenza virus positive children. Results: H1N1 and Yamagata were the prevalent genotypes of influenza A and B virus in Hangzhou, respectively. IL-2, IL-10, and CRP were significantly increased and IFN-γ was decreased in children with severe Influenza A virus infection, and TNF-α and IFN-γ levels were found to be significantly lower in children with severe Influenza B virus infection. Conclusion: Increased IL-2, IL-10, and CRP with decreased IFN-γ may indicate a severe influenza A virus infection, and decreased TNF-α and IFN-γ may indicate a severe influenza B virus infection in children.

Demographic, clinical, and virological characteristics of patients with a laboratory-confirmed diagnosis of influenza during three consecutive seasons, 2015/2016-2017/18, in the Islamic Republic of Iran

BACKGROUND

There are minimal data on the differences in demographics, clinical presentations and outcomes for patients with different types and sub-types of influenza in the Middle East.

OBJECTIVES

To use population-based data from Iran to investigate factors associated with unfavorable disease outcome.

STUDY DESIGN

Clinical data were compiled from the Iranian Ministry of Health for patients of all ages who fulfilled the severe acute respiratory infections (SARI) definition according to World Health Organization criteriatested for any reason and found to have and had laboratory proven influenza September 21, 2015 through March 20, 2018. Pulmonary, cardiac, renal, hematologic and neurologic complications were recorded. Results were compared by type, age, gender and health status. Multivariate analysis was used to analyze risk factors for complications and death.

RESULTS

Of 11,080 enrolled patients, 10,046 (90.7 %) were inpatients, 2254 (20.4 %) were children, 8403 (75.8 %) had influenza A, 2599 (23.5 %) had influenza B, and 78 (0.7 %) had unidentified types. Fever was less common in older patients (OR 0.99; 95 % CI 0.98-0.99, p < 0.001 and in those with comorbidity (OR 0.87; 95 % CI 0.77-0.97, p = 0.013). Although the rate of complications was lower with A(H1N1) pdm09 influenza than with A(H3N2) infection (12.8 % versus 15.6 %, p = 0.001), the mortality rate was higher (7.0 % versus 3.0 %, p < 0.001). Complications occurred more often during late versus early influenza season (OR 1.22; 95 % CI 1.08-1.37, p = 0.002). Patients with type B influenza (OR 0.85; 95 % CI 0.74-0.98, p = 0.025), or who presented with sore throat (OR 0.74; 95 % CI 0.65-0.84, p < 0.001) were less likely to develop complications. The risk of developing complications was increased in patients who had chronic heart disease (OR 1.51; 95 % CI 1.29-1.76, p < 0.001), chronic pulmonary disease (OR 1.62; 95 % CI 1.37-1.91, p < 0.001), diabetes (OR 1.24; 95 % CI 1.03-1.50, p = 022), or epilepsy (OR 1.55; 95 % CI 1.17-2.05). Older age and male gender increased the risk of death but not of complications.

CONCLUSIONS

The clinical features, complications and outcomes of influenza vary by age and by viral type and sub-type. Comorbidites appear to be more important than age in predicting complications.

Circulation of Influenza Type B Lineages in Greece During 2005-2015 and Estimation of Their Impact

The past decades influenza B lineages Victoria and Yamagata cocirculated. Our aim was to estimate the distribution of the two lineages circulating in Greece and any possible mismatching with vaccine influenza B strains. We studied 490 laboratory-confirmed influenza B nonsevere acute respiratory infection (non-SARI) cases diagnosed in the two National Influenza Reference Laboratories by reverse transcriptase polymerase chain reaction from July 1, 2005 to June 30, 2015 and 100 influenza B SARI cases diagnosed from July 1, 2011 to June 30, 2015. Median matching between the circulating influenza B lineages and the vaccine influenza B strains was 19.2% (range: 0-100%) for non-SARI cases during 2005-2015 and 67.6% (range: 41.2-94.1%) for SARI cases during 2011-2015. In two influenza seasons (2005-2006 and 2006-2007), complete lineage mismatch between influenza B non-SARI cases and influenza B vaccine strains was found. We estimated that 5, 12, or 16 laboratory-confirmed SARI cases could have been prevented by quadrivalent influenza inactivated vaccine (QIV) during the 2011-2012 season and 1, 2, or 3 SARI cases during the 2014-2015 season, with a vaccination coverage rate of 70% and a vaccine effectiveness of 20%, 50%, or 70%, respectively. Significant cocirculation of Victoria and Yamagata B strains and mismatching with vaccine influenza B strains were found during 2005-2015 in Greece. The wide use of a QIV instead of a TIV will confer additional immunity and therefore protection against influenza B, and it is expected to prevent several SARI cases annually. Our findings strongly support the recommendations for using QIV.

Surveillance Data for Eight Consecutive Influenza Seasons in Sicily, Italy

Influenza A and B outbreaks occur each year with different activity and molecular patterns. To date, knowledge of seasonal epidemiology remains a prerequisite not only to put in place the most effective immunization strategy against influenza but also to identify population groups at higher risk of developing serious complications. A retrospective analysis of influenza surveillance data from 2010 to 2018 aimed to explore the epidemiology of influenza in Sicily, at the primary care and hospital level. Overall, 6,740 patients with acute respiratory infection were tested, of which 3,032 (45.0%) were positive for influenza. The relative proportion of type A and B viruses markedly varied across seasons. Type A similarly spreads among children and adults, whereas type B was more commonly identified among pediatric population aged 5-9 years. The median age of confirmed influenza cases differed by health-care setting, increasing according to disease severity (range: 8-54 years). Among influenza-confirmed cases, more than 80% of hospitalized patients had an underlying medical condition. Cardiovascular disease, lung disease, diabetes, and obesity were some of the most frequent. Overall, patients admitted to an intensive care unit were more likely to have multiple comorbidities and being infected with influenza infection strongly increased the risk of severe clinical outcomes. Understanding of the epidemiology of influenza and the molecular features of circulating viruses is of paramount importance to optimize prevention and control strategies. Knowledge of predictors for the occurrence of severe forms of the disease may help to address adequate preventive measures to high-risk population groups.

The epidemiological signature of influenza B virus and its B/Victoria and B/Yamagata lineages in the 21st century

We describe the epidemiological characteristics, pattern of circulation, and geographical distribution of influenza B viruses and its lineages using data from the Global Influenza B Study. We included over 1.8 million influenza cases occurred in thirty-one countries during 2000–2018. We calculated the proportion of cases caused by influenza B and its lineages; determined the timing of influenza A and B epidemics; compared the age distribution of B/Victoria and B/Yamagata cases; and evaluated the frequency of lineage-level mismatch for the trivalent vaccine. The median proportion of influenza cases caused by influenza B virus was 23.4%, with a tendency (borderline statistical significance, p = 0.060) to be higher in tropical vs. temperate countries. Influenza B was the dominant virus type in about one every seven seasons. In temperate countries, influenza B epidemics occurred on average three weeks later than influenza A epidemics; no consistent pattern emerged in the tropics. The two B lineages caused a comparable proportion of influenza B cases globally, however the B/Yamagata was more frequent in temperate countries, and the B/Victoria in the tropics (p = 0.048). B/Yamagata patients were significantly older than B/Victoria patients in almost all countries. A lineage-level vaccine mismatch was observed in over 40% of seasons in temperate countries and in 30% of seasons in the tropics. The type B virus caused a substantial proportion of influenza infections globally in the 21^st century, and its two virus lineages differed in terms of age and geographical distribution of patients. These findings will help inform health policy decisions aiming to reduce disease burden associated with seasonal influenza.

Influenza epidemics observed in primary care from 1984 to 2017 in France: A decrease in epidemic size over time

BACKGROUND

Epidemiological analysis of past influenza epidemics remains essential to understand the evolution of the disease and optimize control and prevention strategies. Here, we aimed to use data collected by a primary care surveillance system over the last three decades to study trends in influenza epidemics and describe epidemic profiles according to circulating influenza viruses.

METHODS

Influenza-like illness (ILI) weekly incidences were estimated using cases reported by general practitioners participating in the French Sentinelles network, between 1984 and 2017. Influenza epidemics were detected by applying a periodic regression to this time series. Epidemic (co-)dominant influenza virus (sub)types were determined using French virology data.

RESULTS

During the study period, 297 607 ILI cases were reported allowing the detection of 33 influenza epidemics. On average, seasonal epidemics lasted 9 weeks and affected 4.1% of the population (95% CI 3.5; 4.7). Mean age of cases was 29 years. Epidemic size decreased over time by -66 cases per 100 000 population per season on average (95% CI -132; -0.2, P value = 0.049) and epidemic height decreased by -15 cases per 100 000 (95% CI -28; -2, P value = 0.022). Epidemic duration appeared stable over time. Epidemics were mostly dominated by A(H3N2) (n = 17, 52%), associated with larger epidemic size, higher epidemic peak and older age of cases.

CONCLUSIONS

The declining trend in influenza epidemic size and height over the last 33 years might be related to several factors like increased vaccine coverage, hygiene improvements or changing in influenza viruses. However, further researches are needed to assess the impact of potential contributing factors to adapt influenza plans.

Circulation of influenza A and B in the Czech Republic from 2000-2001 to 2015-2016

Background

To improve national influenza vaccination recommendations, additional data on influenza A and B virus circulation are needed. Here, we describe the circulation of influenza A and B in the Czech Republic during 16 seasons.

Methods

This was a retrospective analysis of data collected from the 2000–2001 to 2015–2016 influenza seasons by the Czech Republic national influenza surveillance network. Influenza was confirmed and viral isolates subtyped by virological assays followed by antigen detection or by reverse transcriptase-polymerase chain reaction.

Results

Of 16,940 samples collected, 5144 (30.4%) were influenza-positive. Influenza A represented 78.6% of positive cases overall and accounted for more than 55.0% of all influenza cases in every season, except for 2005–2006 (6.0%). Both A/H1N1 and A/H3N2 were detected in most seasons, except for 2001–2002 and 2003–2004 (only A/H3N2), and 2007–2008 and 2009–2010 (only A/H1N1). Influenza B represented 21.4% of positive cases overall (range, 0.0–94.0% per season). Both influenza B lineages were detected in three seasons, a single B lineage in 11, and no B strain in two. For the 11 seasons where influenza B accounted for ≥20% of positive cases, the dominant lineage was Yamagata in six and Victoria in four. In the remaining season, the two lineages co-circulated. For two seasons (2005–2006 and 2007–2008), the B lineage in the trivalent influenza vaccine did not match the dominant circulating B lineage.

Conclusions

In the Czech Republic, during the 2000–2001 to 2015–2016 influenza seasons, influenza virus circulation varied considerably. Although influenza A accounted for the most cases in almost all seasons, influenza B made a substantial, sometimes dominant, contribution to influenza disease.

[Description of Influenza B in seasonal epidemics in Spain]

OBJECTIVE

Seasonal influenza epidemics are a major public health concern. They are caused by the influenza A and B viruses; although the A virus is more prominent, influenza B virus infection causes a disease with similar characteristics. There are two phylogenetically distinct influenza B lineages (B/Victoria and B/Yamagata), only one of which is present in the trivalent vaccine formulated each season.

METHODS

Epidemiological data from the Spanish Influenza Surveillance System for 2007 to 2017 were reviewed to establish the relative proportion of each type of virus and the characterization of the B lineages in relation to the composition of the trivalent vaccine.

RESULTS

The median proportion of B (2007-2017) was 27.2% (0.7%-74.8%) vs. 16.3% (0.4%-98.6%) for A-H3 and 44.2% (0.1%-98.0%) for pandemic A-H1N1 (20092017). The B lineages co-circulated in 8/10 seasons and there was mismatch with the B vaccine strain in 4/10 seasons. The B virus was dominant in 2007/08 and 2012/13 throughout Spain. There was a combination of dominance/codominance of influenza B and mismatch with the vaccine lineage in at least one third of epidemic seasons reviewed.

CONCLUSIONS

Epidemiological information on influenza B has been less compiled in comparison with data on the A virus. Influenza virus type B is responsible for a significant number of cases in almost all seasons. The predominant B lineage in each season is unpredictable, affecting the protection conferred by the seasonal vaccine. Spanish epidemiological data support the rationale for a quadrivalent vaccine with both B virus lineages similarly to data from other settings.

Impact of bedside diagnosis of influenza in the paediatric emergency ward

OBJECTIVES

This prospective study performed in the paediatric emergency department of the University Hospital of Saint-Etienne aimed to measure the impact of the 24/7 bedside use of the Veritor™ System (Becton Dickinson) on the reduction of supplementary investigations, hospital stay and antimicrobial use.

METHODS

Influenza virus A and B antigens were detected with a rapid influenza digital immunoassay (DIA) on nasopharyngeal aspirates (NPAs) sampled from the children consulting at the paediatric emergency department between January and March 2016 for influenza-like illness. The same NPA was tested by immunofluorescence and/or molecular routine assays. Before performing the DIA, the clinician filled in a questionnaire listing the tests that he/she would have prescribed in the absence of the rapid testing. The prescription of complementary investigations, antimicrobial treatments and hospital stay were also compared to those of the 3 previous years.

RESULTS

A total of 514 children with flu-like symptoms were included. The use of the DIA at bedside decreased the prescription of blood puncture by 47.9% (21.2% to 6.6%), of chest X-rays by 69.0% (33.3% to 10.3%), of lumbar puncture by 77.8% (7.0% to 1.6%), of urine culture by 79.2% (23.3% to 4.9%), of antibiotic treatments by 70.1% (16.9% to 5.1%), and of hospital stay by 25.0% (27.2% to 20.4%), resulting in a reduction of medical costs estimated to more than €69 000 in a season.

CONCLUSIONS

In addition to delivering a rapid aetiological diagnosis, this strategy saves medical costs and favours an antimicrobial stewardship strategy. However, further prospective studies are needed to confirm our findings.

Cross-Protective Efficacy of Monovalent Live Influenza B Vaccines against Genetically Different Lineages of B/Victoria and B/Yamagata in Ferrets

Background

Currently, two genetic lineages of influenza B virus, B/Victoria and B/Yamagata, are cocirculating in humans in various countries. This situation has raised a question regarding the possibility of cross-protection between B components of live attenuated influenza vaccine (LAIV) belonging to different lineages. This study aimed to assess in naïve ferrets the potential protective activity of monovalent B-LAIVs against challenge with homologous and heterologous wild-type (WT) influenza B viruses.

Methods

Groups of seronegative female ferrets 5-6 months of age were given one dose of monovalent LAIV based on B/Victoria or B/Yamagata lineage virus. Ferrets were challenged 21 days later with B/Victoria or B/Yamagata WT virus. Ferrets were monitored closely for clinical signs and morbidity outcomes including febrile response, body weight loss, nasal symptoms, and level of activity one week prior to vaccination and for three days following vaccination/challenge. Nasal washes were collected three days after vaccination/challenge. Samples of lung tissue were taken three days after challenge. All samples were analyzed for the presence of challenge virus by culturing in embryonated chicken eggs and real-time polymerase chain reaction. Antibody response to vaccination was assessed by routine hemagglutination inhibition assay and microneutralization test.

Results

Vaccination led to intensive production of specific neutralizing and antihemagglutinating antibodies to vaccine virus, protected ferrets from homologous challenge infection, and significantly reduced clinical signs and replication of homologous challenge virus. In contrast, cross-lineage serum antibodies were not detected. However, ferrets vaccinated with monovalent B-LAIV had a significantly lower level of heterologous challenge virus in the respiratory tract than those given challenge virus only.

Conclusions

Monovalent B-LAIV has the potential to be cross-protective against infection with genetically different influenza lineages. Further studies are required to confirm this effect.

Shifting patterns of seasonal influenza epidemics

Seasonal waves of influenza display a complex spatiotemporal pattern resulting from the interplay of biological, sociodemographic, and environmental factors. At country level many studies characterized the robust properties of annual epidemics, depicting a typical season. Here we analyzed season-by-season variability, introducing a clustering approach to assess the deviations from typical spreading patterns. The classification is performed on the similarity of temporal configurations of onset and peak times of regional epidemics, based on influenza-like-illness time-series in France from 1984 to 2014. We observed a larger variability in the onset compared to the peak. Two relevant classes of clusters emerge: groups of seasons sharing similar recurrent spreading patterns (clustered seasons) and single seasons displaying unique patterns (monoids). Recurrent patterns exhibit a more pronounced spatial signature than unique patterns. We assessed how seasons shift between these classes from onset to peak depending on epidemiological, environmental, and socio-demographic variables. We found that the spatial dynamics of influenza and its association with commuting, previously observed as a general property of French influenza epidemics, apply only to seasons exhibiting recurrent patterns. The proposed methodology is successful in providing new insights on influenza spread and can be applied to incidence time-series of different countries and different diseases.

FluHMM: A simple and flexible Bayesian algorithm for sentinel influenza surveillance and outbreak detection

Timely detection of the seasonal influenza epidemic is important for public health action. We introduce FluHMM, a simple but flexible Bayesian algorithm to detect and monitor the seasonal epidemic on sentinel surveillance data. No comparable historical data are required for its use. FluHMM segments a typical influenza surveillance season into five distinct phases with clear interpretation (pre-epidemic, epidemic growth, epidemic plateau, epidemic decline and post-epidemic) and provides the posterior probability of being at each phase for every week in the period under surveillance, given the available data. An alert can be raised when the probability that the epidemic has started exceeds a given threshold. An accompanying R package facilitates the application of this method in public health practice. We apply FluHMM on 12 seasons of sentinel surveillance data from Greece, and show that it achieves very good sensitivity, timeliness and perfect specificity, thereby demonstrating its usefulness. We further discuss advantages and limitations of the method, providing suggestions on how to apply it and highlighting potential future extensions such as with integrating multiple surveillance data streams.

The potential value of crowdsourced surveillance systems in supplementing sentinel influenza networks: the case of France

IntroductionParticipatory surveillance systems provide rich crowdsourced data, profiling individuals and their health status at a given time. We explored the usefulness of data from GrippeNet.fr, a participatory surveillance system, to estimate influenza-related illness incidence in France. Methods: GrippeNet.fr is an online cohort since 2012 averaging ca. 5,000 weekly participants reporting signs/symptoms suggestive of influenza. GrippeNet.fr has flexible criteria to define influenza-related illness. Different case definitions based on reported signs/symptoms and inclusions of criteria accounting for individuals' reporting and participation were used to produce influenza-related illness incidence estimates, which were compared to those from sentinel networks. We focused on the 2012/13 and 2013/14 seasons when two sentinel networks, monitoring influenza-like-illness (ILI) and acute respiratory infections (ARI) existed in France. Results: GrippeNet.fr incidence estimates agreed well with official temporal trends, with a higher accuracy for ARI than ILI. The influenza epidemic peak was often anticipated by one week, despite irregular participation of individuals. The European Centre for Disease Prevention and Control ILI definition, commonly used by participatory surveillance in Europe, performed better in tracking ARI than ILI when applied to GrippeNet.fr data. Conclusion: Evaluation of the epidemic intensity from crowdsourced data requires epidemic and intensity threshold estimations from several consecutive seasons. The study provides a standardised analytical framework for crowdsourced surveillance showing high sensitivity in detecting influenza-related changes in the population. It contributes to improve the comparability of epidemics across seasons and with sentinel systems. In France, GrippeNet.fr may supplement the ILI sentinel network after ARI surveillance discontinuation in 2014.

Influenza virus but not MERS coronavirus circulation in Iran, 2013-2016: Comparison between pilgrims and general population

BACKGROUND

The pilgrimage to Mecca and Karbala bring many Muslims to a confined area. Respiratory tract infections are the most common diseases transmitted during mass gatherings in Hajj, Umrah and Karbala. The aim of this study was to determine and compare the prevalence of Middle East respiratory syndrome coronavirus (MERS-CoV) and influenza virus infections among Iranian general population and pilgrims with severe acute respiratory infections (SARI) returning from Mecca and Karbala during 2013-2016.

METHODS

During 2013-2016, a total of 42351 throat swabs were examined for presence of influenza viruses and MERS-CoV in Iranian general population and pilgrims returning from Mecca and Karbala with SARI by using one step RT-PCR kit.

RESULTS

None of the patients had MERS-CoV but influenza viruses were detected in 12.7% with high circulation of influenza A/H1N1 (47.1%).

CONCLUSION

This study showed the prevalence of influenza infections among Iranian pilgrims and general population and suggests continuing surveillance, infection control and appropriate vaccination especially nowadays that the risk of influenza pandemic threatens the world, meanwhile accurate screening for MERS-CoV is also recommended.

Simulation studies to assess the long-term effects of Japan's change from trivalent to quadrivalent influenza vaccination

BACKGROUND

Since 2013/2014, the WHO has been recommending quadrivalent influenza vaccines (QIV) to prevent seasonal influenza. In 2015, Japan replaced trivalent influenza vaccines (TIV) by QIV. We used computer simulations to calculate how this impacted the epidemiology and to assess its cost-effectiveness.

METHODS

We simulated the seasonal transmission of the four influenza strains A(H1N1), A(H3N2), B/Yamagata and B/Victoria with the individual-based simulation tool 4Flu, using official demographic data and Japanese contact patterns. The model considered maternal protection, immunity boosting, new drift variants and different immunity durations for naturally acquired and vaccination-derived immunity. Starting with the 2015/16 season, simulations were evaluated for 20 years, using either TIV or QIV with the reported vaccination coverage. Costs and years of life saved (YOLSs) were calculated and discounted at 2%, using 2015 as base year.

RESULTS

QIV annually prevents on average 548 influenza cases (4.7% of cases which occur when using TIV; 11.9% of influenza B), 1.62 hospitalizations and 0.078 deaths per 100,000 individuals. In Japan's population of 125.35 million, annually 915.06 YOLYs are gained by QIV and 107.52 million USD are saved (societal perspective) [corrected]. From payer perspective, the ICER is 3698 USD/YOLS.

CONCLUSIONS

QIV is cost-effective (payer perspective) or even cost-saving (societal perspective) in Japan.

Characteristics of seasonal influenza A and B in Latin America: Influenza surveillance data from ten countries

Introduction

The increased availability of influenza surveillance data in recent years justifies an actual and more complete overview of influenza epidemiology in Latin America. We compared the influenza surveillance systems and assessed the epidemiology of influenza A and B, including the spatio-temporal patterns of influenza epidemics, in ten countries and sub-national regions in Latin America.

Methods

We aggregated the data by year and country and characteristics of eighty-two years were analysed. We calculated the median proportion of laboratory-confirmed influenza cases caused by each virus strain, and compared the timing and amplitude of the primary and secondary peaks between countries.

Results

37,087 influenza cases were reported during 2004–2012. Influenza A and B accounted for a median of 79% and, respectively, 21% of cases in a year. The percentage of influenza A cases that were subtyped was 82.5%; for influenza B, 15.6% of cases were characterized. Influenza A and B were dominant in seventy-five (91%) and seven (9%) years, respectively. In half (51%) of the influenza A years, influenza A(H3N2) was dominant, followed by influenza A(H1N1)pdm2009 (41%) and pre-pandemic A(H1N1) (8%). The primary peak of influenza activity was in June-September in temperate climate countries, with little or no secondary peak. Tropical climate countries had smaller primary peaks taking place in different months and frequently detectable secondary peaks.

Conclusions

We found that good influenza surveillance data exists in Latin America, although improvements can still be made (e.g. a better characterization of influenza B specimens); that influenza B plays a considerable role in the seasonal influenza burden; and that there is substantial heterogeneity of spatio-temporal patterns of influenza epidemics. To improve the effectiveness of influenza control measures in Latin America, tropical climate countries may need to develop innovative prevention strategies specifically tailored to the spatio-temporal patterns of influenza in this region.

Epidemiological and clinical characteristics of patients infected with enterovirus D68, France, July to December 2014

In 2014, the United States (US) experienced a nationwide outbreak of enterovirus D68 (EV-D68) infection with 1,152 cases reported mainly in hospitalised children with severe asthma or bronchiolitis. Following the US alert, 11 laboratories of the French enterovirus (EV) surveillance network participated in an EV-D68 survey. A total of 6,229 respiratory samples, collected from 1 July to 31 December 2014, were screened for EV-D68 resulting in 212 EV-D68-positive samples. These 212 samples corresponded to 200 EV-D68 cases. The overall EV-D68 positivity rates among respiratory samples were of 5% (184/3,645) and 1.1% (28/2,584) in hospitalised children and adults respectively. The maximum weekly EV-D68 positivity rates were of 16.1% for children (n = 24/149; week 43) and 2.6% for adults (n = 3/115; week 42). Of 173 children with EV-D68 infection alone, the main symptoms were asthma (n = 83; 48.0%) and bronchiolitis (n = 37; 21.4%). One child developed acute flaccid paralysis (AFP) following EV-D68-associated pneumonia. Although there was no significant increase in severe respiratory tract infections reported to the French public health authorities, 10.7% (19/177) of the EV-D68 infected children and 14.3% (3/21) of the EV-D68 infected adults were hospitalised in intensive care units. Phylogenetic analysis of the viral protein 1 (VP1) sequences of 179 EV-D68 cases, revealed that 117 sequences (65.4%), including that of the case of AFP, belonged to the B2 variant of clade B viruses. Continuous surveillance of EV-D68 infections is warranted and could benefit from existing influenza-like illness and EV surveillance networks.

Paediatric antibiotic prescriptions in primary care in the Alpes-Maritimes area of southeastern France between 2008 and 2013

France has remained among the top five European countries for ambulatory antibiotic consumption since such monitoring began in 1998. Young children are major antibiotic consumers, in spite of the viral origin of most infections in this population. Recommendations were updated in 2011 to limit prescriptions. In order to assess their impact, diagnoses and prescriptions were compared in a population of children attending daycare centres in southeastern France in 2008 and 2012. Trends in the reimbursement of paediatric antibiotic prescriptions by the national health insurance (NHI) for the whole area were also studied. Distribution of diagnoses accounting for antibiotic treatment and type of antibiotic prescribed over the previous 3 months to children below 4 years of age attending daycare centres in the Alpes-Maritimes area in southeastern France were compared between 2008 and 2012 prior to and following the availability of these new recommendations. Trends in reimbursed ambulatory antibiotic prescriptions by general practitioners and paediatricians in the area were studied for this age group from 2008 to 2012 and in 2013. The majority of recorded diagnoses concerned upper respiratory tract infections (URTI). Inappropriate antibiotic prescription persisted for colds and bronchitis in similar proportions during both surveys. Improvement in the choice of antibiotic with fewer prescriptions for third-generation cephalosporins was observed both in daycare centres and according to NHI data; however, this was mainly recorded among paediatricians. The management of paediatric URTI still needs improvement, pointing to the need to investigate and adequately address the reasons for inappropriate antibiotic prescription.

Epidemiology of influenza B in Australia: 2001-2014 influenza seasons

Background

Influenza B is characterised by two antigenic lineages: B/Victoria and B/Yamagata. These lineages circulate together with influenza A during influenza seasons, with varying incidence from year to year and by geographic region.

Objective

To determine the epidemiology of influenza B relative to influenza A in Australia.

Methods

Laboratory‐confirmed influenza notifications between 2001 and 2014 in Australia were obtained from the Australian National Notifiable Diseases Surveillance System.

Results

A total of 278 485 laboratory‐confirmed influenza cases were notified during the study period, comprising influenza A (82.2%), B (17.1%) and ‘other and untyped’ (0.7%). The proportion of notifications that were influenza B was highest in five‐ to nine‐year‐olds (27.5%) and lowest in persons aged 85 years and over (11.5%). Of all B notifications with lineage determined, 77.1% were B/Victoria and 22.9% were B/Yamagata infections. Mismatches between the dominant B lineage in a season and the trivalent vaccine B lineage occurred in over one‐third of seasons during the study years. In general, influenza B notifications peaked later than influenza A notifications.

Conclusion

The proportion of circulating influenza B in Australia during 2001‐2014 was slightly lower than the global average and was dominated by B/Victoria. Compared with influenza A, influenza B infection was more common among older children and young adults and less common in the very elderly. Influenza B lineage mismatch with the trivalent vaccine occurred about one‐third of the time.

Public health and economic impact of seasonal influenza vaccination with quadrivalent influenza vaccines compared to trivalent influenza vaccines in Europe

Influenza B strains represent on average 23% of all circulating strains in Europe and when there is a vaccine mismatch on B strains, additional influenza-related hospitalizations and deaths as well as substantial additional costs are observed. The objective was to estimate the public health and economic impact of seasonal influenza vaccination with quadrivalent influenza vaccines (QIV) compared to trivalent influenza vaccines (TIV) in Europe (EU).

Based on data from 5 EU countries (France, Germany, Italy, Spain and UK) during 10 influenza seasons from 2002 to 2013, epidemiological and associated economic outcomes were estimated for each season for the actual scenario where the TIV was used, and for a hypothetical scenario where QIV could have been used instead.

By using QIV, this study estimated that for the 5 EU countries, an additional 1.03 million (327.9/100,000 inhabitants) influenza cases, 453,000 (143.9/100,000) general practitioners consultations, 672,000 (213.1/100,000) workdays lost, 24,000 (7.7/100,000) hospitalizations and 10,000 (3.1/100,000) deaths could have been avoided compared to the use of TIV over the 10-seasons-period. This study estimates that QIV can be of economic value since from a societal perspective 15 million Euros would have been saved on general practitioners consultations (14 million Euros from third-party payer perspective), 77 million on hospitalizations (74 million Euros from third-party payer perspective) and 150 million Euros on workdays lost, across the 5 EU countries.

In conclusion, the present study estimates that, compared to TIV, QIV may result in a substantial decrease in epidemiological burden and in influenza-related costs.

Characterization of influenza activity based on virological surveillance of influenza-like illness in tropical Singapore, 2010-2014

Singapore is situated in the tropics where the seasonality of influenza is not as well defined as that of temperate countries. We examined the circulation of influenza viruses in the community in terms of the characteristics of influenza activity. We reviewed laboratory-confirmed virological data collected between 2010 and 2014 under the national influenza surveillance programme. Influenza activity was measured by the proportion of specimens from outpatients with influenza-like illness tested positive for influenza virus based on 4-weekly moving interval. Seasonal epidemics occurred around the end of previous year or the beginning and middle of the year. Increases in influenza positivity were more pronounced when there was a change in the predominant circulating influenza virus type/subtype to influenza A(H3N2). Influenza epidemics lasted about 12 weeks on average, with longer duration when there was a change in the predominant influenza type/subtype and especially when it was associated with influenza A(H3N2). Continuous influenza surveillance is important as it could provide early warning of imminent surges in virus transmission, and allow for timely implementation of public health prevention and control interventions to minimize influenza-associated disease burden. J. Med. Virol. 88:2069-2077, 2016. © 2016 Wiley Periodicals, Inc.

Evaluation of the Alere i Influenza A&B assay for rapid identification of influenza A and influenza B viruses

The Alere i Influenza A&B assay is a novel isothermal nucleic acid amplification assay capable of detecting and differentiating influenza A and B viruses in approximately 15 min with minimal hands-on time. This study was conducted in order to assess the performance of the Alere i Influenza A&B assay compared to molecular techniques, considered to be gold standard methods, to evaluate the results. A total of 119 nasopharyngeal swabs collected from inpatients with influenza-like illness were included in the study using both archived and prospectively collected samples from adults and children. Prospectively collected samples were also compared to the Alere BinaxNOW® Influenza A & B Card. The overall sensitivity for detection of influenza A and B viruses compared to those of molecular techniques were 65.96 % and 53.33 % respectively, while the specificity was 98.51 % and 95.96 %. Compared to the Alere BinaxNOW® Influenza A & B Card, the Alere i assay is considerably more sensitive for detection of influenza A and B viruses, although both tests demonstrated excellent specificity for diagnosis of influenza viruses.

Influenza vaccination in high-risk groups: a revision of existing guidelines and rationale for an evidence-based preventive strategy

Influenza, an infectious respiratory disease, is one of the main causes of excess winter deaths (EWDs) in Europe. Annual flu epidemics are associated with high morbidity and mortality rates, especially among the elderly, those with underlying health conditions and pregnant women. Health Care Workers (HCWs) are also considered at high risk of both contracting influenza and spreading the virus to vulnerable patients. During the 2014/2015 season, the excess winter mortality rates observed in countries of the northern hemisphere (EuroMOMO network) and in Italy (+13%) were strongly related to the intensity of influenza circulation. Influenza vaccination is the most important public health intervention to prevent seasonal influenza transmission and infection. However, to date, influenza vaccination coverage reported in Europe (including high-risk groups) is still largely unsatisfactory. This study analyzes some international and European guidelines on influenza vaccination and the rationale that underlies evidence- based public health intervention for the prevention of influenza among the principal high-risk groups: a) the elderly (subjects aged 65 years or older); b) subjects with underlying health conditions; c) pregnant women; d) healthcare workers. Only by achievement recommended influenza vaccination coverage among high-risk groups in all European countries can we reduce the burden of disease.