Primary care data

Influenza activity

For week 15/2017, 59 (14%) of 416 sentinel specimens tested positive for influenza viruses (Table). Of these, 95% were type B and 5% type A viruses. The proportion of type B viruses commonly increases in the second half of an influenza season.

Of 9 countries across the region that each tested at least 10 sentinel specimens, only 2 reported proportions of influenza virus detections of 30% or above.  Of 2 subtyped A viruses, both were A(H3N2). The lineage of 18 influenza B viruses was determined, of which 2 were B/Yamagata and 16 B/Victoria lineages.  

Since week 40/2016, of all typed viruses, 90% were type A, with 99% of those subtyped being A(H3N2) (Table). Of the 758 influenza B viruses that have been ascribed to a lineage since week 40/2016, 428 (56%) were of the B/Yamagata lineage and 330 (44%) were of the B/Victoria lineage.

Table. Influenza virus detections in sentinel-source specimens by type and subtype, week 15/2017 and cumulatively

Virus type and subtype

Current Week

Season 2016-2017

Number

%a

Number

%a

Influenza A

 3

5

16 219

90

A(H1N1)pdm09

 0

0

186

1

A(H3N2)

 2

100

13 540

99

A not subtyped

 1

-

2 493

-

Influenza B

56

95

1 749

10

B/Victoria lineage

16

89

 330

44

B/Yamagata lineage

2

11

 428

56

Unknown lineage

38

-

991

-

Total detections / Total tested

 59 / 416

14

    17 968 / 49 048

37

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.