Surveillance of Influenza in Northern Ireland 2014-2015

The 2014/15 influenza season was characterised by moderate levels of influenza activity.  Primary care consultation rates were higher than in 2013/14 for the majority of the season, although still low overall.  Activity seen in other surveillance was also higher than in 2013/14 year, and showed that the severity and impact of influenza was greater in 2014/15 and affected older age groups most frequently, with more reported respiratory outbreaks, patients with confirmed influenza admitted to Intensive Care Units/High Dependency Units and excess mortality in those over 65 years of age.

Influenza A (H3) was the predominant circulating strain (75%), followed by influenza B (19%) later in the season. A small number of influenza A (H1N1) pdm09 cases were also detected. Strain characterisation carried out nationally showed that the majority of influenza A(H3) and B strains had drifted from the strains contained in the 2014/15 Northern Hemisphere influenza vaccine.