Flu Update – Week 09, 2015

March 10, 2015

Update by Dr J Gallagher, Employment Health Advisors (EHA):

Influenza activity in Ireland remained elevated in community and hospital settings during the week ending 1st March 2015 (week 9 2015), with some indicators of influenza activity decreasing.

The sentinel GP influenza-like illness (ILI) consultation rate was 53.4 per 100,000 population in week 9 2015, a decrease compared to the updated rate of 60.0 per 100,000 population during week 8 2015.  ILI rates have remained above the Irish baseline threshold (21.0/100,000 population) for eight consecutive weeks. ILI rates were highest in 5-14 year olds during week 9 2015.  The proportion of influenza–related calls to GP Out-of-Hours services decreased during week 9 2015.

Influenza positivity remained elevated during week 9 2015. Influenza A(H3) is the predominant circulating influenza virus this season. Respiratory syncytial virus (RSV) positivity has continued to decrease since the peak of activity during the last two weeks in December.  The latest complete data on respiratory admissions reported from a network of sentinel hospitals were elevated. 86 confirmed influenza hospitalised cases were notified to HPSC during the week ending 1st March 2015, a decrease from 116 cases reported during the previous week. The median age of confirmed influenza hospitalised cases to date this season is 58 years.  Fifteen influenza-associated deaths have been reported to HPSC this season, with a median age of 81 years.

Ten acute respiratory general outbreaks were reported to HPSC during the week ending 1st March 2015: five of these outbreaks were associated with influenza and five acute respiratory outbreaks had no pathogens identified. The majority of confirmed influenza outbreaks this season have been associated with influenza A(H3) in residential care facilities for the elderly.

In Europe, increased influenza activity has continued, in particular in western and central European countries.  The number and percentage of influenza virus detections in sentinel specimens showed a slight reduction in what might be described as a high plateau phase of the influenza season.

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