[Source: EuroFlu, full page: (LINK). Extract.]

EuroFlu - Weekly Electronic Bulletin - Week 7 : 10/02/2014-16/02/2014 - 21 February 2014, Issue No. 518

Influenza activity continues to increase across Europe

Summary, week 07/2014
  • Consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) have continued to increase in most of the WHO European Region.
  • Nevertheless, there is evidence of Influenza activity migrating from south to north, as activity decreased in some southern countries where the season started earlier.
  • Influenza A(H1N1)pdm09 and A(H3N2) viruses continued to co-circulate in the Region, with A(H1N1)pdm09 remaining predominant.
  • The number of reported hospitalizations due to severe acute respiratory infection (SARI) has increased slowly over the last several weeks in association with increasing influenza activity in the eastern part of the Region.
  • The WHO Consultation on the Composition of Influenza Virus Vaccines for the Northern Hemisphere 2014?2015 took place, and the WHO expert group recommended no change compared to the vaccine composition for the 2013-2014 season.

The EuroFlu bulletin describes and comments on influenza activity in the 53 Member States in the WHO European Region to provide information to public health specialists, clinicians and the public on the timing of the influenza season, the spread of influenza, the prevalence and characteristics of circulating viruses (type, subtype and lineage) and severity.

For a description of influenza surveillance in the WHO European Region see below.

Virological surveillance for influenza

During week 07/2014, a total of 14 357 specimens from sentinel and non-sentinel sources was tested for influenza, 3029 (21%) of which were positive: 2904 (96%) influenza A and 125 (4%) influenza B (Fig. 1 and 2).


Influenza A has remained the dominant virus type across the Region since week 40/2013.

Of the 1851 influenza A viruses that were subtyped during week 07/2014, 1106 (60%) were A(H1N1)pdm09 and 745 (40%) A(H3N2), showing an increase in the proportion of influenza A(H3N2) viruses from the previous week (Fig. 2a).

Since the beginning of weekly monitoring (week 40/2013), sentinel and non-sentinel sources have yielded 18 614 influenza detections: 17 793 (96%) were influenza A and 821 (4%) influenza B viruses (Fig. 2b).

Of the 12 969 influenza A viruses that have been subtyped, 8024 (62%) were A(H1N1)pdm09 and 4945 (38%) were A(H3N2).

In addition, since week 40/2013, the lineage of 83 influenza B viruses has been determined: 76 (92%) belonged to the B/Yamagata lineage (the B lineage virus recommended by WHO for inclusion in trivalent seasonal influenza vaccines) and 7 (8%) to B/Victoria.



For week 07/2014, 27 countries reported influenza A as the dominant type (Map 1 and country table). In countries providing data on dominant subtypes, influenza A(H3N2) was reported as dominant in 7 countries (Armenia, Georgia, Ireland, Luxembourg, the Republic of Moldova, Slovenia and Ukraine), while 11 countries (Bulgaria, Estonia, Finland, Germany, Iceland, Latvia, Norway, Portugal, Spain, Sweden and the United Kingdom (Scotland)) reported A(H1N1)pdm09 as dominant. 6 countries (Belgium, France, Greece, Italy, the Russian Federation and Switzerland) reported A(H1N1)pdm09 and A(H3N2) as co-dominant.

Virus strain characterizations

Circulating influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic similarity to the viruses included in the seasonal influenza vaccine, and determine the prevalence of mutations that affect pathogenicity or are associated with susceptibility to antiviral drugs.

For the 2013/2014 northern hemisphere influenza season, WHO recommended inclusion of A/California/7/2009 (H1N1)pdm09-like, A/Texas/50/2012 (H3N2)-like and B/Massachusetts/2/2012-like (Yamagata lineage) viruses in vaccines (see the WHO headquarters web site).

The WHO Consultation on the Composition of Influenza Virus Vaccines for the Northern Hemisphere 2014?2015 took place in week 7/2014, and the WHO expert group recommended no change from the vaccine composition for the 2013?2014 season. (see the WHO headquarters web site).

Since week 40/2013, 463 influenza viruses characterized antigenically by 11 countries (Denmark, Finland, Germany, Latvia, Norway, Portugal, Romania, the Russian Federation, Slovakia, Switzerland and the United Kingdom (England)) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3).

12 countries (Belgium, Denmark, Finland, Germany, Greece, Ireland, the Netherlands, Norway, Portugal, the Russian Federation, Spain and Sweden) have characterized 438 influenza viruses genetically (Fig. 4).


# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2013/2014 northern hemisphere influenza season.

* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2014 southern hemisphere influenza season.

Monitoring of susceptibility to antiviral drugs

Since week 40/2013, 8 countries (Greece, the Netherlands, Norway, Portugal, Spain, Sweden, the Russian Federation and the United Kingdom (England)) have screened 498 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

Of the 387 A(H1N1)pdm09 viruses tested, 385 showed susceptibility to both drugs. 2 viruses carrying the neuraminidase H275Y amino acid substitution, causing resistance to oseltamivir, were detected in the United Kingdom in hospitalized patients treated with oseltamivir.

Of the 88 influenza A(H3N2) viruses tested, 87 showed susceptibility to both drugs. The remaining virus, detected in the United Kingdom in a hospitalized immunocompromised patient treated with oseltamivir, carried the neuraminidase E119V amino acid substitution and showed reduced inhibition by oseltamivir but normal inhibition by zanamivir.

All 23 influenza B viruses tested showed susceptibility to both oseltamivir and zanamivir.

So far, there is no indication of increased resistance to the neuraminidase inhibitors during the winter of 2013?2014. All 80 influenza A(H1N1)pdm09 and 64 influenza A(H3N2) viruses screened for susceptibility to adamantanes were found to be resistant.

Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)

During week 07/2014, most European countries continued to report low-intensity influenza activity (Map 2), but with more countries reporting increasing trends than during previous weeks (Map 4). Regarding geographic spread, influenza activity was predominantly regional or widespread, particularly in countries in southern and western Europe (Map 3).

During week 07/2014, consultation rates increased in most countries in the Region. In most of the 22 countries with established national thresholds, the rates had reached or surpassed threshold levels. At the same time, however, consultation rates continued to decrease in Bulgaria, Portugal and Spain, where the influenza season started earlier.


During week 07/2014, 652 sentinel specimens tested positive for influenza. The percentage of sentinel ILI/ARI specimens testing positive for influenza in week 07/2014 was much lower to that reported in week 07/2013 (Fig. 5).


During week 07/2014, 652 (35%) of the 1848 specimens collected from sentinel sources tested positive for influenza, the majority being influenza A (Fig. 6a). Click here for a detailed overview in a table format.


Hospital surveillance for SARI

For surveillance of severe disease due to influenza, the number of SARI hospitalizations for influenza was similar to those in previous weeks, and the percentage testing positive has increased to 36% in the past 2 weeks. Most SARI cases were reported in those aged 0?4 years (Fig. 7).


During week 07/2014, 81 (36%) of the 224 SARI samples collected in Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine tested positive for influenza A, the majority being A(H3N2) (Fig. 8a). Click here for a detailed overview in table format.


For week 7/2014, 6 countries (Finland, Ireland, Romania, Spain, Sweden and the United Kingdom) reported 221 hospitalized, laboratory-confirmed influenza cases, including 117 cases admitted to intensive care units (ICUs).

Since week 40/2013, 7 countries have reported 2531 hospitalized, laboratory-confirmed influenza cases: 2508 (99%) were related to influenza virus type A infection and 23 (1%) to type B virus infection.

A total of 1695 influenza A viruses has been subtyped, 1339 (79%) were A(H1)pdm09 and 356 (21%) were A(H3).

Since week 40/2013, 7 countries have reported a total of 209 fatal cases. All were associated with influenza virus type A infection and 154 of them were subtyped: 125 (81%) as A(H1)pdm09 and 29 (19%) as A(H3).

SARI and hospitalized laboratory-confirmed influenza cases reported to the European Centre for Disease Prevention and Control (ECDC) differ in that the former include a higher proportion of influenza B and a lower proportion of influenza A(H1N1)pdm09 than the latter.

Overall, fewer influenza detections were reported in countries with SARI surveillance, which can be explained by low influenza activity in most of these countries up to week 06/2014.

Further, the participating countries use different surveillance systems and this may lead to differences in influenza (sub)type detections.

For more information on surveillance of confirmed hospitalized influenza, please see ECDC?s Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.

Respiratory syncytial virus (RSV)

Based on the data presented by countries reporting on RSV, the positivity rate had been gradually increasing since week 40/2013, peaked in week 50/2013 and has decreased in all the reporting countries since. This represents a slightly later start than in the previous season (see Country data and graphs for individual country data).

EuroMOMO (European Mortality Monitoring Project)

EuroMOMO is a project set up to develop and operate a routine public health mortality monitoring system to detect and measure, on a real-time basis, excess deaths related to influenza and other possible public health threats across 20 European Union (EU) countries.

Pooled analysis of week data for 07/2014 showed that all-cause mortality was within the normal range for all reporting countries. Results of pooled analysis may vary, depending on which countries are included in the weekly analysis.

For more information about the EUROMOMO mortality monitoring system please click here.


Country comments (where available)

Republic of Moldova: 41 samples were tested for Influenza A and B: 21 - were positive for RNA Influenza virus A(H3N2), 1 - positive for RNA Influenza virus A(H1N1)pdm, 1 -positive for RNA A(H3N2)+DNA Adenovirus, and 2 - for RNA RSV.