Primary care data

Influenza activity

For weeks 21-26/2017, a median of 26 countries (range 19 to 29) reported weekly epidemiological data. All reporting countries reported low intensity for the duration of this period. 

 

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

For weeks 21-26/2017, 31 (4%) of 820 sentinel specimens tested positive for influenza viruses (Table) and the number of detections showed a decreasing trend over this period . Of all typed viruses, 71% were type B and most of these have not been ascribed to a lineage.

Table. Influenza virus detections in sentinel-source specimens by type and subtype, cumulatively for weeks 21-26/2017

Virus type and subtype

Weeks 21-26/2017

Number

%a

Influenza A

 9

29

A(H1N1)pdm09

 6

75

A(H3N2)

 2

25

A not subtyped

 1

-

Influenza B

22

71

B/Victoria lineage

 5

83

B/Yamagata lineage

 1

17

Unknown lineage

 16

-

Total detections / Total tested

 31 /  820

4


 a
For 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.