Influenza Vaccination

Influenza Vaccination

By Dr Ying Yu  General Practitioner

Influenza (flu) is a group of viruses that mainly affect the respiratory system. Causative influenza viruses are usually classified as group A, B, or C.  Influenza can spread easily.

A person with influenza can be infectious to others 24 hours before the start of symptoms until one week after symptoms.  Symptoms usually subside in 5-8 days in previously healthy individuals.  People of all ages can be infected with influenza.

Influenza usually has a sudden onset. Common symptoms include fever, dry, non-productive cough, nasal congestion, headache, sore throat and constitutional symptoms, including muscle aches and fatigue.

A nasal or throat swab done at the GP office or at home using the SARS-CoV-2/Influenza A/B/RSV Antigen Rapid Test Kit within 4 days of symptoms onset can diagnose influenza. Negative RAT tests should be taken with caution due to their relative insensitivity.

Influenza has a fatality rate of around 0.3%. The highest fatality rate happens in people over the age of 85.

In Australia, influenza vaccine is available free under the National Immunisation Program for people most at risk of severe influenza infection, including:

  • children aged 6 months to less than 5 years
  • people aged 65 and over
  • Aboriginal and Torres Strait Islander people aged 6 months and over
  • pregnant women
  • people with certain medical conditions aged 6 months and over

Egg allergy is not a contraindication to the influenza vaccine.  People with an egg allergy, including anaphylaxis, can be safely vaccinated with influenza vaccines.

Vaccination before the onset of each influenza season is recommended. The period of influenza circulation is typically June to September in NSW.  ATAGI advises that optimal protection occurs within the first three to four months following vaccination. Vaccination from mid-April/May onwards will likely result in peak immunity during the influenza season.  It is never too late to vaccinate since influenza can circulate all year round.

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