Seasonal influenza (flu) surveillance

The Influenza Surveillance Bulletin describes influenza activity in Northern Ireland and is produced weekly or fortnightly by the PHA during the flu season.

Influenza is an acute viral infection of the respiratory tract (nose, mouth, throat, bronchial tubes and lungs). There are three types of flu virus: A, B and C, with A and B responsible for most clinical illness. Influenza activity in Northern Ireland is monitored throughout the year to inform public health action and to prevent spread of the infection.

The flu season typically runs from week 40 to week 20. Week 40 for the 2019/20 season commenced on 1 October 2019.

To see the 2019/2020 flu bulletins click here.

Surveillance systems used to monitor influenza activity in Northern Ireland include:

  • GP ‘flu/flu-like-illness’ (‘flu/FLI’) surveillance representing 98% of the population
  • GP Out-of-Hours (OOH) surveillance system representing 100% of the population
  • Sentinel flu-spotter GP practices representing 11.2% of the population
  • Virological reports of flu and RSV from the Regional Virus Laboratory (RVL) and local laboratories (as outlined in the influenza weekly surveillance bulletin)
  • Intensive care unit/high dependency unit (ICU/HDU) laboratory confirmed flu cases reported by Critical Care Network for Northern Ireland (CCaNNI)
  • Hospital (non-ICU/HDU) laboratory confirmed flu cases
  • Laboratory confirmed flu outbreak notifications reported to PHA Health Protection duty room
  • Mortality data from Northern Ireland Statistics and Research Agency (NISRA) of selected respiratory infections (some of which may be attributable to flu)
  • Excess mortality estimations are calculated using the EuroMOMO (Mortality Monitoring in Europe) model based on raw death data supplied by NISRA

Previous flu bulletins

To see the 2018/2019 flu bulletins click here.

Annual Surveillance Reports

Surveillance of Influenza in Northern Ireland 2018-19

Surveillance of Influenza in Northern Ireland 2017-18

Surveillance of Influenza in Northern Ireland 2016-17

Surveillance of Influenza in Northern Ireland 2015-16

Surveillance of Influenza in Northern Ireland 2014-2015

Surveillance of Influenza in Northern Ireland 2013-2014 

Surveillance of influenza in Northern Ireland 2012-2013

Surveillance of influenza in Northern Ireland 2011-2012