What is influenza (flu)?
Influenza (flu) is a contagious viral infection that affects the respiratory system. It can cause fever, chills, headache, muscle aches, cough, sore throat, and tiredness. Flu can be serious, especially for older adults, pregnant people, young children, and those with long‑term health conditions, sometimes leading to complications such as pneumonia or hospital admission.
What is the influenza vaccine?
The influenza vaccine helps protect against the most common strains of flu virus expected to circulate each winter. The vaccine used in the UK is updated every year to match circulating strains.
Different types of flu vaccine are used depending on age and health status, including:
- Injected inactivated vaccines (cannot cause flu)
- Live attenuated nasal spray vaccine (used mainly in children)
Your healthcare professional will offer the most appropriate vaccine for you.
Why should I have the flu vaccine?
The flu vaccine:
- Reduces your risk of catching flu
- Makes flu symptoms milder if you do get it
- Reduces the risk of serious complications
- Helps protect vulnerable people by reducing spread
Annual vaccination is recommended because protection decreases over time and flu viruses change each year.
Who is eligible for the flu vaccine in the UK?
The flu vaccine is recommended and usually offered free on the NHS to:
- Adults aged 65 years and over
- Pregnant people
- Children (as part of the NHS childhood flu programme)
- People with certain long‑term health conditions
- People with weakened immune systems
- Carers and household contacts of vulnerable individuals
- Frontline health and social care workers
Private vaccination is also available for those not eligible for a free NHS vaccine.
How is the vaccine given?
- Adults and most children: injection into the upper arm
- Most children aged 2–17 years: nasal spray
The vaccination usually takes only a few minutes.
Common side effects
Most side effects are mild and short‑lived, including:
- Soreness, redness, or swelling at the injection site
- Mild fever
- Headache, muscle aches, or tiredness
- Runny or blocked nose (nasal spray vaccine)
These usually resolve within a few days.
Less common or serious side effects
- Allergic reactions are rare but can occur. Symptoms may include rash, swelling, breathing difficulties, or collapse. Medical help should be sought immediately if these occur.
- Guillain‑Barré syndrome is extremely rare following flu vaccination.
Your healthcare professional is trained to manage rare serious reactions.
Who should not have the flu vaccine?
Please inform the healthcare professional if you:
- Have had a severe allergic reaction to a previous flu vaccine or any of its ingredients
- Are currently unwell with a high fever (vaccination may be delayed)
- Have specific immune conditions (relevant mainly for the nasal spray vaccine)
Most people can safely receive the flu vaccine.
Effectiveness
The flu vaccine does not give 100% protection, but it significantly reduces the risk of severe illness, complications, and hospitalisation.
Consent statement
By agreeing to receive the influenza vaccine, you confirm that:
- You have read and understood the information provided
- You have had the opportunity to ask questions and received satisfactory answers
- You understand the benefits and possible risks of the vaccine
- You consent to the administration of the influenza vaccine
