Dominant influenza A(H3N2) and B/Yamagata virus circulation in EU/EEA, 2016/17 and 2017/18 seasons, respectively

Members of the European Influenza Surveillance Network: Portugal (Figueiredo Augusto Gonçalo, Machado Jorge, Moreira Guiomar Raquel, Nogueira Paulo, Rebelo de Andrade Helena, Rodrigues Ana Paula)The yearly influenza epidemics during each winter season vary in burden and severity. During the 2016/17 and 2017/18 seasons, all-cause excess mortality was observed during periods of high influenza virus circulation. Our aim is to describe and compare the pattern of influenza virus circulation and related disease severity by number of patients and fatal cases in intensive care units (ICUs) across European Union/European Economic Area (EU/EEA) countries for the seasons 2016/17 and 2017/18. As influenza circulation progressed from a west to east direction across Europe in 2017/18, a better understanding of the current epidemiological situation might help to prepare countries in the eastern part of the World Health Organization (WHO) European Region for high influenza activity and severity.info:eu-repo/semantics/publishedVersio

Predominance of influenza A(H1N1)pdm09 virus genetic subclade 6B.1 and influenza B/Victoria lineage viruses at the start of the 2015/16 influenza season in Europe

Members of the World Health Organization European Region and European Influenza Surveillance Network of the reporting countries - Portugal: Raquel Guiomar, Pedro Pechirra, Paula Cristovão, Inês Costa, Patrícia Conde, Baltazar Nunes, Ana RodriguesInfluenza A(H1N1)pdm09 viruses predominated in the European influenza 2015/16 season. Most analysed viruses clustered in a new genetic subclade 6B.1, antigenically similar to the northern hemisphere vaccine component A/California/7/2009. The predominant influenza B lineage was Victoria compared with Yamagata in the previous season. It remains to be evaluated at the end of the season if these changes affected the effectiveness of the vaccine for the 2015/16 season.info:eu-repo/semantics/publishedVersio

Very little influenza in the WHO European Region during the 2020/21 season, weeks40 2020 to 8 2021

Funding: ECDC and WHO internal funds. Publisher Copyright: © This is an open-access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0) Licence. You may share and adapt the material, but must give appropriate credit to the source, provide a link to the licence and indicate if changes were made.Between weeks40 2020 and 8 2021, the World Health Organization European Region experienced a 99.8% reduction in sentinel influenza virus positive detec-tions (33/25,606 tested; 0.1%) relative to an average of 14,966/39,407 (38.0%; p<0.001) over the same time in the previous six seasons. COVID-19 pandemic public health and physical distancing measures may have extinguished the 2020/21 European seasonal influenza epidemic with just a few sporadic detections of all viral subtypes. This might possibly continue dur-ing the remainder of the influenza season. We study features of influenza epidemiology in the World Health Organization (WHO) European Region from week40 2020 to week8 2021, a period when in usual seasons the highest influenza activity (peak of seasonal epidemic) would be expected. Results are compared to those of the previous six seasons (2014/15-2019/20).Peer reviewe

Very little influenze in the WHO European Region during the 2020/21 season, weeks 40 2020 to 8 2021

Between weeks 40 2020 and 8 2021, the World Health Organization European Region experienced a 99.8% reduction in sentinel influenza virus positive detections (33/25,606 tested; 0.1%) relative to an average of 14,966/39,407 (38.0%; p < 0.001) over the same time in the previous six seasons. COVID-19 pandemic public health and physical distancing measures may have extinguished the 2020/21 European seasonal influenza epidemic with just a few sporadic detections of all viral subtypes. This might possibly continue during the remainder of the influenza season

Spotlight influenza: The 2019/20 influenza season and the impact of COVID-19 on influenza surveillance in the WHO European Region.

BackgroundAnnual seasonal influenza activity in the northern hemisphere causes a high burden of disease during the winter months, peaking in the first weeks of the year.AimWe describe the 2019/20 influenza season and the impact of the COVID-19 pandemic on sentinel surveillance in the World Health Organization (WHO) European Region.MethodsWe analysed weekly epidemiological and virological influenza data from sentinel primary care and hospital sources reported by countries, territories and areas (hereafter countries) in the European Region.ResultsWe observed co-circulation of influenza B/Victoria-lineage, A(H1)pdm09 and A(H3) viruses during the 2019/20 season, with different dominance patterns observed across the Region. A higher proportion of patients with influenza A virus infection than type B were observed. The influenza activity started in week 47/2019, and influenza positivity rate was ≥ 50% for 2 weeks (05-06/2020) rather than 5-8 weeks in the previous five seasons. In many countries a rapid reduction in sentinel reports and the highest influenza activity was observed in weeks 09-13/2020. Reporting was reduced from week 14/2020 across the Region coincident with the onset of widespread circulation of SARS-CoV-2.ConclusionsOverall, influenza type A viruses dominated; however, there were varying patterns across the Region, with dominance of B/Victoria-lineage viruses in a few countries. The COVID-19 pandemic contributed to an earlier end of the influenza season and reduced influenza virus circulation probably owing to restricted healthcare access and public health&nbsp;measures.</p

Start of the 2014/15 influenza season in Europe: drifted influenza A(H3N2) viruses circulate as dominant subtype36933

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Alternating patterns of seasonal influenza activity in the WHO European Region following the 2009 pandemic, 2010-2018.

BACKGROUND: Influenza virus infections are common and lead to substantial morbidity and mortality worldwide. We characterized the first eight influenza epidemics since the 2009 influenza pandemic by describing the distribution of viruses and epidemics temporally and geographically across the WHO European&nbsp;Region. METHODS: We retrospectively analyzed laboratory-confirmed influenza detections in ambulatory patients from sentinel sites. Data were aggregated by reporting entity and season (weeks 40-20) for 2010-2011 to 2017-2018. We explored geographical spread using correlation&nbsp;coefficients. RESULTS: There was variation in the regional influenza epidemics during the study period. Influenza A virus subtypes alternated in dominance, except for 2013-2014 during which both cocirculated, and only one season (2017-2018) was B virus dominant. The median start week for epidemics in the Region was week 50, the time to the peak ranged between four and 13&nbsp;weeks, and the duration of the epidemic ranged between 19 and 25&nbsp;weeks. There was evidence of a west-to-east spread across the Region during epidemics in 2010-2011 (r&nbsp;=&nbsp;.365; P&nbsp;=&nbsp;.019), 2012-2013 (r&nbsp;=&nbsp;.484; P&nbsp;=&nbsp;.001), 2014-2015 (r&nbsp;=&nbsp;.423; P&nbsp;=&nbsp;.006), and 2017-2018 (r&nbsp;=&nbsp;.566; P&nbsp;&lt;&nbsp;.001) seasons. Variation in virus distribution and timing existed within reporting entities across seasons and across reporting entities for a given&nbsp;season. CONCLUSIONS: Aggregated influenza detection data from sentinel surveillance sites by season between 2010 and 2018 have been presented for the European Region for the first time. Substantial diversity exists between influenza epidemics. These data can inform prevention and control efforts at national, sub-national, and international levels. Aggregated, regional surveillance data from early affected reporting entities may provide an early warning function and be helpful for early season forecasting&nbsp;efforts.</p

Start of the 2014/15 influenza season in Europe: drifted influenza A(H3N2) viruses circulate as dominant subtype

The influenza season 2014/15 started in Europe in week 50 2014 with influenza A(H3N2) viruses predominating. The majority of the A(H3N2) viruses characterised antigenically and/or genetically differ from the northern hemisphere vaccine component which may result in reduced vaccine effectiveness for the season. We therefore anticipate that this season may be more severe than the 2013/14 season. Treating influenza with antivirals in addition to prevention with vaccination will be important.S