Primary care data

Influenza activity

All 35 countries reporting on influenza activity for week 19/2017 reported low intensity. However, of the 36 countries reporting on geographic spread of influenza, 2 reported regional and 15 local or sporadic influenza activity, indicating that influenza viruses are still circulating; 19 countries reported no influenza activity.

The overall proportion of sentinel influenza virus detections among sentinel specimens was 6% compared to 12% in the previous week. Influenza viruses were detected in only seven countries (Armenia, Germany, Kosovo, Lithuania, the Russian Federation, Turkey and the United Kingdom (Northern Ireland and Scotland)).

 

Viruses detected in sentinel-source specimens (ILI and ARI)

For week 19/2017, 15 (6%) of 264 sentinel specimens tested positive for influenza viruses (Table). All were type B viruses.

Of 7 countries across the region that each tested at least 10 sentinel specimens, 2 reported proportions of influenza virus detections of 10% or above (Armenia and United Kingdom (Scotland)).

Since week 40/2016, of all typed viruses, 89% were type A, with 99% of those subtyped being A(H3N2) (Table). Of the 817 influenza B viruses that have been ascribed a lineage since week 40/2016, 455 (56%) were of the B/Yamagata lineage and 362 (44%) were of the B/Victoria lineage.

Table. Influenza virus detections in sentinel-source specimens by type and subtype, week 19/2017 and cumulatively

Virus type and subtype

Current Week

Season 2016-2017

Number

%a

Number

%a

Influenza A

0

0

16 235

89

A(H1N1)pdm09

 0

0

186

1

A(H3N2)

 0

0

13 569

99

A not subtyped

0

-

2 480

-

Influenza B

15

100

1 911

11

B/Victoria lineage

2

40

 362

44

B/Yamagata lineage

3

60

 455

56

Unknown lineage

10

-

1 094

-

Total detections / Total tested

 15 / 264

6

    18 146/ 50 653

36

aFor influenza type percentage calculations, the denominator is total detections; for subtype and lineage, it is total influenza A subtyped and total influenza B lineage determined, respectively; for total detections, it is total tested.