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

EuroFlu - Weekly Electronic Bulletin - Week 4 : 20/01/2014-26/01/2014 - 31 January 2014, Issue No. 515

Slowly increasing influenza activity in Europe

Summary, week 04/2014
  • Influenza activity has increased slowly but steadily over the past weeks, mainly in the southern countries in the WHO European Region.
  • Activity in the remaining countries has been lower than in the same period of the 2012/2013 season.
  • Nevertheless, in week 04/2014 most countries reported increasing trends.
  • Since the beginning of the season, influenza A has been predominant in the Region, with the majority of outpatient detections reported by Spain, where the influenza season started earlier than in other countries.
  • The number of hospitalized laboratory-confirmed influenza cases reported has increased over the last several weeks in southern and western European countries, with 87% of the cases during week 04/2014 being associated with A(H1N1)pdm09 infection.

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 04/2014 a total of 10 749 specimens from sentinel and non-sentinel sources was tested for influenza, 1568 (15%) of which were positive: 1513 (96%) influenza A and 55 (4%) influenza B (Fig. 1 and 2).

France and Spain reported the majority of influenza-positive cases.


Influenza A has remained dominant since week 40/2013. Of the 1060 influenza A viruses that were subtyped during week 04/2014, 638 (60%) were A(H1N1)pdm09 and 422 (40%) A(H3N2) (Fig. 2a).

Since the beginning of weekly monitoring (week 40/2013), sentinel and non-sentinel sources have yielded 7969 influenza detections, with an increasing proportion of influenza A viruses: 7513 (94%) were influenza A and 456 (6%) influenza B viruses (Fig. 2b).

Of the 5473 influenza A viruses that have been subtyped, 3076 (56%) were A(H1N1)pdm09 and 2397 (44%) were A(H3N2).

In addition, since week 40/2013, the lineage of 54 influenza B viruses has been determined: 50 (93%) belonged to the B/Yamagata lineage (the B lineage virus recommended by WHO for inclusion in trivalent seasonal influenza vaccines) and 4 (7%) to B/Victoria.



Similarly to week 03/2014, 17 countries reported influenza A as the dominant type during week 04/2014 (Map 1 and country table).

In countries providing data on dominant subtypes, influenza A(H3N2) was reported as dominant in Ireland, Slovenia, the former Yugoslav Republic of Macedonia and Turkey, while Bulgaria, Greece, Latvia, Norway, Spain and the United Kingdom (Scotland) reported A(H1N1)pdm09 as dominant. France, 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).

Since week 40/2013, 122 influenza viruses characterized antigenically by 9 countries (Denmark, Finland, Germany, Latvia, Portugal, Romania, the Russian Federation, 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).

8 countries (Belgium, Denmark, Finland, the Netherlands, Norway, Portugal, Spain and Sweden) have characterized 224 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, 6 countries (the Netherlands, Norway, Portugal, Spain, Sweden and the United Kingdom (England)) have screened 288 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

Of the 203 A(H1N1)pdm09 viruses tested, 201 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 with no known exposure to neuraminidase inhibitors.

There is no indication of the spread of resistant viruses.

Of the 64 influenza A(H3N2) viruses tested, 63 showed susceptibility to both drugs. The remaining virus, detected in the United Kingdom in a hospitalized patient treated with oseltamivir, carried the neuraminidase E119V amino acid substitution and showed reduced inhibition by oseltamivir but normal inhibition by zanamivir.

All 21 influenza B viruses tested showed susceptibility to oseltamivir and zanamivir. All 57 influenza A(H1N1)pdm09 and 47 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 04/2014, most European countries continued to report low-intensity influenza activity (Map 2), with increasing trends (Map 4).

Regarding geographic spread, influenza activity was predominantly sporadic (Map 3), with only Bulgaria, Greece, Spain and the United Kingdom (England) reporting widespread activity.

During week 04/2014, despite an overall increasing trend, ILI and ARI consultation rates remained below the national thresholds in the 17 countries in the WHO European Region that have established epidemic thresholds, except Albania, Israel and Switzerland.


During week 04/2014, 554 sentinel specimens tested positive for influenza, with 252 (45%) being reported by Spain.


During week 04/2014, 554 (28%) of the 1958 specimens collected from sentinel sources tested positive for influenza, the majority being influenza A (H3N2) (Fig. 6a). Click here for a detailed overview in a table format.


Hospital surveillance for SARI

The number of SARI hospitalizations decreased slightly compared to the previous week, with most cases occurring in the group aged 0?4 years (Fig. 7).


During week 04/2014, 11 (7%) of the 148 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, with 7 being A(H1N1)pdm09 (Fig. 8a), correlating with the late start of the season in central and eastern parts of the Region. (Fig. 8a). Click here for a detailed overview in table format.


Since week 40/2013, France, Ireland, Romania, Spain, Sweden and the United Kingdom have reported 1177 hospitalized laboratory-confirmed influenza cases in total: 17 influenza B, 633 A(H1N1)pdm09, 152 A(H3) and 375 type A not subtyped.

Since week 40/2013. France, Spain and Ireland reported 71 fatal cases in total. All fatal cases were associated with influenza type A infection and 50 were subtyped: 39 (78%) as A(H1)pdm09 and 11 (22%) A(H3).

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 has been gradually increasing since week 40/2013 and picked up in week 50/2013 giving a slightly later start compared to 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 04/2014 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: This week were tested for Influenza A and B 22 samples: 6 of them were positive for RNA Influenza A(H3N2); 1 sample was positive for RNA hRSV, and 2 - for DNA Adenovirus.