Weeks 30–34/2017 (24 July – 27 August 2017)
- Influenza activity was at out-of-season levels in all countries. All reporting countries continued to report low intensity of influenza activity.
- Influenza viruses were detected sporadically both in sentinel and non-sentinel specimens, with both influenza type A and B viruses detected.
- For week 34/2017, data from the 20 countries or regions reporting to the EuroMOMO project indicated all-cause mortality to be at expected levels.
Additional information on global influenza activity is available from WHO’s biweekly global updates.
2016/17 season overview
- After an earlier start than usual (week 46/2016), influenza activity peaked between weeks 52/2016 and 4/2017. Between weeks 12 and 20/2017, most countries reported decreasing influenza activity with the proportion of sentinel detections returning to the epidemic threshold value (10%) in week 17/2017.
- A(H3N2) viruses predominated by a large margin during the season.
- Significant mortality from all causes was observed in people aged 15–64, and markedly so in people aged 65 or older, in the majority of the 20 reporting countries or regions. This is commonly seen when the predominant viruses circulating are A(H3N2).
- Two-thirds of the A(H3N2) viruses genetically characterized belonged to subclade 3C.2a1, but remained antigenically similar to the clade 3C.2a vaccine virus, as described in the WHO recommendations for vaccine composition for the northern hemisphere 2017–18. See also the ECDC summary report for June.