Giuseppe
Emeritus
[Source: EuroFlu, full page: (LINK). Extracts, edited.]
EuroFlu - Weekly Electronic Bulletin -
Week 16 : 16/04/2012-22/04/2012 - 27 April 2012, Issue N? 443
Influenza activity declining in the WHO European Region
Current situation: week 16/2012
Outpatient surveillance for influenza-like illness (ILI) and acute respiratory infection (ARI)
38 countries reported on trends in clinical activity: 16 stable; 4 increasing and 18 decreasing.
Of the 38 countries reporting on the geographical spread of influenza: 7 reported no activity; 20, sporadic activity; 7, local activity; 1, regional activity; and 3, widespread activity.
All countries reported either medium (2) or low intensity (36).
During week 16/2012 sentinel outpatient clinics collected 538 respiratory specimens, of which 120 (22%) tested positive for influenza viruses, a slight decrease from the previous week.
Of the positive specimens, 58 (48%) were influenza type A and 62 (52%) were influenza B (Table 1, Fig. 1).
In the 9 countries testing 20 or more sentinel specimens, influenza positivity ranged from 5% to 30%, with a median of 24% (mean: 20%).
Hospital surveillance for SARI
7 countries reported data for hospital-based sentinel surveillance of SARI: Belarus, Georgia, Kazakhstan, Kyrgyzstan, Romania, the Russian Federation and Ukraine.
87 respiratory specimens were collected from SARI patients, of which 15 (17%) were positive for influenza: 12 were type A and 3 were type B. All influenza A viruses were subtyped as A(H3). (Fig. 2).
Further information on the sentinel SARI surveillance systems represented in the EuroFlu bulletin can be found in ?Overview of sentinel SARI systems in EuroFlu?.
Virological overview
During week 16/2012, 39 countries reported on whether there was a dominant virus based on both sentinel and non-sentinel detections.
11 countries reported influenza A and/or A(H3N2) as the dominant virus; 3 reported influenza B, and 2 reported co-dominance of influenza B and A(H3N2). 23 countries reported that no virus was dominant.
Influenza virus type and subtype detections
Table 1 provides an overview of the influenza virus detections by type and subtype in sentinel ILI/ARI and SARI surveillance for both the current week and the period since week 40/2011.
Table 1. Influenza virus detections in sentinel specimens
[Specimens tested and viruses - Current week (number and %): ILI/ARI ? SARI - Cumulative since week 40 (number and %): ILI/ARI ? SARI]
During week 16/2012, 811 specimens from non-sentinel sources were reported positive for influenza: 647 (80%) type A and 164 (20%) type B.
Of the influenza A viruses, 325 were subtyped: 317 (98%) as A(H3N2) and 8 (2%) as A(H1N1)pdm09.
Since week 40/2011, 41 214 influenza viruses from sentinel and non-sentinel sources have been typed: 37 708 (91%) were influenza A and 3506 (9%) were influenza B.
Of the influenza A viruses, 20 377 were subtyped: 19 536 (96%) as A (H3N2) and 841 (4%) as A(H1N1)pdm09.
Virus strain characterizations
Influenza viruses are monitored each season for antigenic and genetic characteristics, to determine the extent to which they correspond with the viruses included in the seasonal influenza vaccine as well as the occurrence of mutations that affect pathogenicity or that are associated with susceptibility to antiviral drugs.
Since week 40/2011, 17 countries (Austria, the Czech Republic, Denmark, the United Kingdom (England), France, Germany, Greece, Hungary, Italy, Latvia, Portugal, Romania, the Russian Federation, Slovakia, Slovenia, Sweden, Switzerland) have characterized 1801 influenza viruses antigenically (Fig. 3).
16 countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Norway, Portugal, the Russian Federation, Spain, Sweden, Switzerland) have characterized 1181 influenza viruses genetically (Fig. 4).
# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2011/2012 northern hemisphere influenza season.
* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2012 southern hemisphere influenza season.
Further information
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Further information can be obtained from the WHO/Europe, WHO headquarters and European Centre for Disease Prevention and Control web sites.
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EuroFlu - Weekly Electronic Bulletin -
Influenza activity declining in the WHO European Region
Current situation: week 16/2012
- This issue is based on data for week 16/2012 reported by 42 Member States in the WHO European Region.
- Consultation rates continue to decrease or have stabilized in most countries.
- The percentage of influenza-positive cases is decreasing but has a higher proportion of influenza B viruses than in previous weeks.
- The number of hospitalizations due to severe acute respiratory infection (SARI) and the influenza-positivity rate are relatively stable.
- Influenza A(H3N2) viruses continue to dominate, with co-circulation of influenza B and A(H1N1)pdm09 viruses.
Outpatient surveillance for influenza-like illness (ILI) and acute respiratory infection (ARI)
38 countries reported on trends in clinical activity: 16 stable; 4 increasing and 18 decreasing.
Of the 38 countries reporting on the geographical spread of influenza: 7 reported no activity; 20, sporadic activity; 7, local activity; 1, regional activity; and 3, widespread activity.
All countries reported either medium (2) or low intensity (36).
During week 16/2012 sentinel outpatient clinics collected 538 respiratory specimens, of which 120 (22%) tested positive for influenza viruses, a slight decrease from the previous week.
Of the positive specimens, 58 (48%) were influenza type A and 62 (52%) were influenza B (Table 1, Fig. 1).
In the 9 countries testing 20 or more sentinel specimens, influenza positivity ranged from 5% to 30%, with a median of 24% (mean: 20%).
Hospital surveillance for SARI
7 countries reported data for hospital-based sentinel surveillance of SARI: Belarus, Georgia, Kazakhstan, Kyrgyzstan, Romania, the Russian Federation and Ukraine.
87 respiratory specimens were collected from SARI patients, of which 15 (17%) were positive for influenza: 12 were type A and 3 were type B. All influenza A viruses were subtyped as A(H3). (Fig. 2).
Virological overview
During week 16/2012, 39 countries reported on whether there was a dominant virus based on both sentinel and non-sentinel detections.
11 countries reported influenza A and/or A(H3N2) as the dominant virus; 3 reported influenza B, and 2 reported co-dominance of influenza B and A(H3N2). 23 countries reported that no virus was dominant.
Influenza virus type and subtype detections
Table 1 provides an overview of the influenza virus detections by type and subtype in sentinel ILI/ARI and SARI surveillance for both the current week and the period since week 40/2011.
Table 1. Influenza virus detections in sentinel specimens
[Specimens tested and viruses - Current week (number and %): ILI/ARI ? SARI - Cumulative since week 40 (number and %): ILI/ARI ? SARI]
- Specimens tested ? 538 - 87 - 34862 - 4050
- Influenza A + B - 120 (22.3%) - 15 (17.2%) - 10709 (30.7%) - 630 (15.6%)
- Influenza A - 58 (48.3%) - 12 (80.0%) - 9410 (87.9%) - 595 (94.4%)
- Influenza B - 62 (51.7%) - 3 (20.0%) - 1299 (12.1%) - 35 (5.6%)
- Influenza A subtyped - 42 - 12 - 8484 - 562
- A (H1N1)pdm09 - 4 (9.5%) - 0 (0.0%) - 167 (2.0%) - 64 (11.4%)
- A (H3N2) - 38 (90.5%) - 12 (100.0%) - 8317 (98.0%) - 498 (88.6%)
- A (H1N1) ? 0 (0.0%) - 0 (0.0%) - 0 (0.0%) - 0 (0.0%)
Of the influenza A viruses, 325 were subtyped: 317 (98%) as A(H3N2) and 8 (2%) as A(H1N1)pdm09.
Since week 40/2011, 41 214 influenza viruses from sentinel and non-sentinel sources have been typed: 37 708 (91%) were influenza A and 3506 (9%) were influenza B.
Of the influenza A viruses, 20 377 were subtyped: 19 536 (96%) as A (H3N2) and 841 (4%) as A(H1N1)pdm09.
Virus strain characterizations
Influenza viruses are monitored each season for antigenic and genetic characteristics, to determine the extent to which they correspond with the viruses included in the seasonal influenza vaccine as well as the occurrence of mutations that affect pathogenicity or that are associated with susceptibility to antiviral drugs.
Since week 40/2011, 17 countries (Austria, the Czech Republic, Denmark, the United Kingdom (England), France, Germany, Greece, Hungary, Italy, Latvia, Portugal, Romania, the Russian Federation, Slovakia, Slovenia, Sweden, Switzerland) have characterized 1801 influenza viruses antigenically (Fig. 3).
16 countries (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Norway, Portugal, the Russian Federation, Spain, Sweden, Switzerland) have characterized 1181 influenza viruses genetically (Fig. 4).
# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2011/2012 northern hemisphere influenza season.
* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2012 southern hemisphere influenza season.
Further information
The EuroFlu bulletin describes and comments on influenza activity in the 53 countries in the WHO European Region. Further information can be obtained from the WHO/Europe, WHO headquarters and European Centre for Disease Prevention and Control web sites.
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