Primary care data
Overall, the majority of countries reported low activity of respiratory infections, based on syndromic surveillance data for influenza-like illness (ILI) and/or acute respiratory infection (ARI). Epidemic thresholds have been passed in 8 reporting countries, indicating influenza activity based on ILI or ARI rates: Ireland, Israel, Italy, the Netherlands, Norway, Spain, Switzerland and the United Kingdom (England, Scotland and Wales).
For week 1/2018, low intensity of influenza activity was reported by 28 of the 46 countries reporting on this indicator, medium intensity of influenza activity was reported by 15 countries, and 3 countries reported high intensity (Ireland, Italy and United Kingdom (Northern Ireland)). No geographic spread of influenza was reported by only 3 of the 45 countries reporting on this indicator; 19 countries reported sporadic cases, 3 reported local geographic spread, 4 countries reported regional spread, and 16 countries reported widespread activity.
Viruses detected in sentinel-source specimens (ILI and ARI)
For week 1/2018, 803 (41.8%) of 1 919 sentinel specimens tested positive for influenza viruses. Of these, 28% were type A and 72 % were type B. Out of 153 subtyped A viruses, 63% were influenza A(H1N1)pdm09 and 37% A(H3N2). Of 136 B viruses ascribed to a lineage, 96% were B/Yamagata and 4% B/Victoria.
Of 29 countries across the region that each tested at least 10 sentinel specimens in week 1/2018, 16 in northern, western and southern European areas reported proportions of influenza virus detections of at least 30% or more (median of 44%, range of 30% to 100%).
Since week 40/2017, more influenza type B (65%) than type A (35%) viruses have been detected. Of 1 127 subtyped A viruses, 60% were A(H1N1)pdm09. The majority of type B viruses were reported without lineage, but of the 729 ascribed to a lineage, 96% were B/Yamagata.
Details of the distribution of viruses detected in non-sentinel-source specimens can be found in the Virus characteristics section.