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Influenza (commonly known as flu) is highly infectious and causes acute viral infection of the respiratory tract. This virus is spread through droplets, aerosol or direct contact with respiratory secretions from an infected individual. The usual incubation period is one to three days.

For healthy individuals, influenza is unpleasant but usually self-limiting with recovery between two to seven days. Some people are at increased risk of it causing severe illness or even death. Complications of influenza can include:

  • Bronchitis
  • Secondary bacterial pneumonia
  • Otitis media (in children)
  • Meningitis
  • Encephalitis or
  • Meningoencephalitis

Those at greatest risk of serious illness from influenza include:

  • Babies
  • Older people
  • Those with certain underlying health conditions
  • People who are immunosuppressed
  • Pregnant women


Influenza vaccines

Most influenza vaccines available in the UK are inactivated with the exception of the live attenuated influenza vaccine (LAIV) – this is the vaccine given to most eligible children. The brand name for LAIV available in the UK is Fluenz®Tetra. LAIV contains live viruses that have been attenuated (weakened) and cold adapted so that they can only replicate in the lower temperatures of the nasal passages.

Because of the changing nature of influenza viruses, and changes in the strains circulating and causing disease, the World Health Organization (WHO) monitors the epidemiology of the influenza viruses throughout the world and makes annual recommendations about which strains should be included for the upcoming winter.

The World Health Organization (WHO) has announced recommendations for the viral composition of influenza vaccines for the 2022-23 influenza season in the northern hemisphere.


Summary of product characteristics

There are a number of inactivated influenza vaccines available. You can find out more about each vaccine in the summary of product characteristics (SmPC) which can be found at the link below by entering the vaccine name:


Recommended vaccines



Vaccination programme recommendations from the Joint Committee on Vaccination and Immunisation (JCVI) and Welsh Government policy can be found at the links below.

Joint Committee on Vaccination and Immunisation - GOV.UK (read JCVI publications and statements; search e.g. influenza)


Welsh Health Circulars and Welsh Government letters


Training resources

The national flu immunisation programme 2023-24 – training slides v1 

The FluTwo eLearning module has been updated for 2023/24 and can be accessed via ESR or the Learning @Wales platform. Further information and user guides are available here: E-learning.

The Flu/COVID-19 One eLearning module has been updated for 2023/24 and can be accessed via ESR or the Learning @Wales platform. Further information and user guides are available here: E-learning. This short animation, has been produced to promote the Flu/COVID-19 One eLearning module.

Further immunisation training information and resources are provided on the Training Resources and Events page.


Clinical resources and information

Keep in mind that vaccine eligibility information in Wales and England differs.


Patient group directions (PGDs) and protocols

PGD templates for the influenza vaccine can be found on the Patient group directions (PGDs) and protocols page.


Further clinical resources and information


Flu template resources

Vaccination Champion resources


Data and surveillance