Flu, or influenza, is a viral infection that mainly affects our respiratory system (nose, throat and lungs). It's extremely variable and changes over time, and different strains are in circulation so a new flu vaccine has to be prepared each year.

Flu usually starts with a sudden fever, muscle aches and pains affecting limbs and joints, feeling very tired and weak, shivering and having the chills, sore throat, a runny or blocked nose, and having a dry and chesty cough.

It can cause severe illness and even death among vulnerable groups including older people or people with an underlying health conditions, and can cause complications for pregnant women.

You can read more about the symptoms of flu on the NHS website.

How does the flu jab work?

The flu jab stimulates your body's immune system to make antibodies to attack the flu virus.

Antibodies are proteins that recognise and fight off germs, such as viruses, that have invaded your blood.

If you're exposed to the flu virus after you've had the flu jab, your immune system will recognise the virus and immediately produce antibodies to fight it.

It may take 10 to 14 days for your immunity to build up fully after you've had the flu vaccine.

In February each year the World Health Organisation (WHO) assesses the strains of flu virus that are most likely to be circulating over the following winter months. Based on this assessment WHO recommends which flu strains the flu jab should contain each winter.

Who should get the flu jab?

The NHS have a list of eligible groups of people who should have their flu jab every year and for these groups the flu jab is free from your GP or local pharmacy.

These include those who are:

  • 65 years old or over;
    You're eligible for the flu vaccine this year (2019/20) if you'll be aged 65 and over on 31 March 2020.

  • pregnant; 
    You're advised to have the flu jab regardless of the stage of pregnancy, as pregnant women have an increased risk of developing complications if they get flu.

  • have certain medical conditions;
    For example: chronic respiratory disease such as asthma, COPD, bronchitis, chronic heart disease, chronic kidney disease, chronic neurological conditions such as Parkinson's disease, MS, motor neurone disease, have a condition that weakens your immune system such as HIV, or on chemotherapy. If you have a long term health condition your GP can advise whether you can have the flu jab for free.

  • living in a long-term residential care home;

  • receive a carer's allowance, or you are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill;

  • staff working in health and social care settings;

  • children;
    Please check the NHS website for more information about the children’s flu vaccine.

You can read more about who is eligible for a free flu jab on the NHS website.

If you're not eligible for a free flu jab, it's still a good idea to get the flu jab to protect yourself from the unpleasant symptoms and protect the people in your community. You can pay privately for a flu jab from most high street pharmacies.