What is flu?

15th May 2019

What is flu?

Influenza, or flu, is a highly contagious respiratory illness caused by influenza viruses. There are two main types of influenza virus that cause infection in humans – types A and B – and many sub-types or strains. Flu can occur throughout the year but flu activity usually peaks in winter.

Flu is a vaccine-preventable illness but a new vaccine needs to be given each year because flu viruses change (mutate) constantly. A new flu vaccine is prepared each year to best match the strains predicted for the coming flu season.

What are the symptoms?

People with flu typically experience some or all of the following symptoms for at least a week:

  • fever and chills
  • cough, sore throat and runny or stuffy nose
  • muscle aches, joint pains, headaches and fatigue (feeling very tired)
  • nausea, vomiting and diarrhoea (more common in children than adults)

Seek immediate medical advice if the illness quickly becomes worse or if any of the following occurs:

  • shortness of breath or rapid breathing
  • chest pain
  • confusion or sudden dizziness
  • persistent vomiting

How is it spread?

  • Flu viruses are mainly spread by droplets made when an infected person coughs or sneezes
  • Flu can also spread after touching surfaces where infected droplets have landed
  • Flu can be spread to someone by an infected person even before their symptoms begin
  • Adults with flu are infectious from the day before their symptoms start until 5-7 days later
  • Young children and people with weakened immune systems may be infectious for longer.

How is it prevented?

Flu vaccination each year before winter arrives is the best way to prevent flu.

Healthy respiratory hygiene also helps to prevent the spread of flu.

  • Cover your mouth with your elbow when you cough or sneeze
  • Stay at home if you’re sick
  • Wash your hands frequently

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