Flu Influenza Immunisation

Overview

Flu (influenza) is a common illness caused by flu viruses. It spreads easily from person to person and tends to arrive in waves each winter. Flu immunisation — often called the flu jab or flu shot — is a vaccine that helps your body build protection before you meet the virus. It is usually given as a quick injection in the upper arm, and some countries offer a nasal spray version for young children. Because flu viruses change over time, the vaccine is reviewed and offered again each year.

Flu is very common. It spreads widely most winters, and the flu vaccine is one of the most widely used vaccines in the world. Millions of people are vaccinated each year.

Anyone can get flu, and anyone can benefit from vaccination. Some groups are offered it first because flu can hit them harder: people aged 65 and over, pregnant women, young children, people with long-term health conditions (such as heart, lung, kidney or liver problems, diabetes, or a weakened immune system), people living in care homes, and people who care for or work with vulnerable people.

Symptoms

Common symptoms

• A sudden high temperature (fever) or feeling shivery and cold
• Aching muscles and feeling generally exhausted
• A dry cough and sore throat
• Headache
• Feeling sick, or loose stools (poo) in some people
• Difficulty sleeping and low energy for several days

Symptoms in children

• High fever, sometimes with febrile seizures (fits caused by fever) in young children
• Being unusually sleepy, clingy or hard to wake
• Ear pain or ear infection
• Not drinking enough, or fewer wet nappies than usual
• Tummy pain, vomiting or loose stools
• A cough that may last a week or more

Symptoms in older adults

• Fever may be absent or lower than expected
• New confusion or unusual drowsiness
• Worsening of existing heart or lung conditions
• Falls or difficulty getting around
• Dehydration and poor appetite
• Chest infections that follow on from flu

Causes

Main causes

• Flu is caused by influenza viruses, mainly two types that are common in people.
• The viruses spread through tiny droplets when someone with flu coughs, sneezes or talks.
• They can also spread by touching surfaces with virus on them and then touching your mouth, nose or eyes.
• Flu spreads most easily in crowded indoor places and during the colder months.
• The viruses change slightly from year to year, which is why last year's vaccine may not fully cover this year's flu.

Risk factors

• Being aged 65 or over, or a very young child
• Being pregnant, or having recently given birth
• Long-term conditions such as asthma, lung disease, heart disease, diabetes, kidney or liver disease
• A weakened immune system, from illness or from some treatments
• Living in a care home or other shared living setting
• Working in healthcare or social care, or being a carer
• Smoking
• Being very overweight
• Living in crowded or shared housing

When to see a doctor

See a doctor urgently if:

• You or your child has trouble breathing, chest pain, or is hard to wake
• A fever in a baby under 3 months
• Symptoms improve and then suddenly get worse
• You have a long-term condition that is getting harder to manage
• You are pregnant and develop a high fever or feel very unwell
• You have a weakened immune system and think you may have flu

Book a routine appointment if:

• You want to know whether you are eligible for the free flu vaccine
• You have questions about the vaccine, including if you have an allergy history or are pregnant
• You have had a reaction after a previous vaccine
• Your flu-like symptoms have lasted more than a week or keep coming back
• You need advice about vaccination for a child who is nervous of needles

Diagnosis

For most people, flu is recognised from the pattern of symptoms and from knowing that flu is going around locally — no test is needed. When you go for immunisation, there is no test to take beforehand: a nurse or pharmacist will simply check a short list of questions, such as whether you are unwell with a fever that day, whether you are pregnant, and whether you have had a reaction to a vaccine before. That is to make sure the timing is right and the vaccine is safe for you.

Tests that may be done

• Usually no test is needed to diagnose flu
• Sometimes a swab from the nose or throat is sent to a lab, mainly for people in hospital or at high risk
• Blood tests are not routine for flu
• Before vaccination: no blood test or screening test is required

What to expect at your appointment

If you have symptoms, your appointment will mostly be a conversation about how you feel, how long it has lasted, and whether you have any long-term conditions. Your blood pressure, temperature and breathing may be checked. For vaccination, expect a short appointment of a few minutes: a quick check of your details, the vaccine itself, and advice to sit for a short while afterwards — usually around 15 minutes if you have had reactions to vaccines before.

Treatment

There are two sides to treatment: protecting yourself with the yearly flu vaccine, and managing flu if you do catch it. Most people get better at home with rest and fluids. Some people at higher risk may be offered antiviral medicines by a doctor — these work best when started early, so it is worth asking quickly if you are in a higher-risk group.

Self-care at home

• Rest and stay warm; plan for a few days in bed
• Drink plenty of fluids — water, warm drinks, or oral rehydration drinks if you are not eating
• Take simple pain or fever relief if you need it, and check with your pharmacist which option suits you, especially if you take other medicines, are pregnant, or are treating a child
• Stay home and avoid close contact with others while you have a fever, to avoid passing flu on
• Cover coughs and sneezes, and wash your hands often
• Keep rooms ventilated by opening a window where you can
• Children can be given small, frequent drinks and gentle foods; do not worry if appetite is low for a day or two

Medical treatments

Treatment depends on how unwell you are and your risk level. For most healthy people, treatment is rest, fluids and symptom relief at home. For people in higher-risk groups — for example those with long-term conditions, pregnant women, or people with a weakened immune system — a doctor may prescribe antiviral medicines. These are not the same as antibiotics (which do not work on viruses). Antivirals work best when started in the first day or two of symptoms, so contact your doctor early rather than waiting. Antibiotics are only used if a bacterial infection such as pneumonia develops alongside flu.

When is surgery considered?

Surgery is not used to treat flu or to give the flu vaccine. In rare cases, flu can lead to complications such as a build-up of pus around the lungs, which may need a procedure in hospital — but this is uncommon.

Living with this condition

If you have flu, the main job is to rest and give your body time. Expect to feel very tired for several days and to have a cough that lingers for a week or two. Plan for time off work or school and ask for help with shopping, cooking or childcare. After vaccination, most people carry on as normal straight away. You may have a slightly sore arm, mild aching or a mild fever for a day or two — this is a sign your immune system is responding and it settles on its own.

Lifestyle tips

• Get the flu vaccine each year, ideally in early autumn before flu season starts
• Wash your hands regularly and keep shared surfaces clean
• Cover your mouth and nose when you cough or sneeze
• Open windows and meet people in well-ventilated spaces when flu is going around
• Avoid visiting people who are vulnerable if you feel unwell
• If you smoke, stopping is one of the best ways to protect your lungs — ask your doctor or pharmacist for support

Diet and exercise

There is no special diet that prevents flu, but eating regularly and drinking enough helps your body cope. While you are unwell, aim for simple, nourishing food and plenty of fluids, and pause your usual exercise until you feel better. Once you are recovering, build activity back gradually — a short walk first, then more as your energy returns. If you have a heart or lung condition that exercise affects, ask your care team what is right for you.

Mental health and emotional wellbeing

Being unwell can be draining, and it is normal to feel low, anxious or frustrated when you are stuck at home. Some people also feel nervous about needles or about vaccines in general — this is very common, and it is fine to say so when you book. Tell the nurse or pharmacist, who can suggest ways to make it easier, such as a calm room, a distraction, or lying down for the injection. If worry or low mood is affecting your daily life, please speak to your doctor. If you ever feel you cannot keep yourself safe, contact your local crisis line or emergency services right away — help is available and you deserve it.

Prevention

Flu cannot be prevented completely, but yearly vaccination is the single most effective way to reduce your risk. Good hand hygiene, ventilation, staying home when unwell and avoiding close contact with people who are ill all help reduce spread.

Vaccines

A flu vaccine is offered every year, usually in autumn. It is given as a small injection in the upper arm for most adults, and a nasal spray is offered to many young children in some countries. Vaccination is recommended for everyone who is offered it, and especially for people at higher risk and those who live or work closely with them. It is safe in pregnancy and is recommended at any stage of pregnancy. If you feel unwell with a fever on the day, you may be asked to come back once you are better. You cannot catch flu from the vaccine.

Screening programmes

There is no screening test for flu. Instead, countries run seasonal vaccination programmes and invite the people most at risk. If you have not been invited but think you are eligible, ask your doctor, nurse or pharmacist.

Complications

If left untreated

• Chest infection or pneumonia, which can be serious especially in older adults
• Worsening of existing long-term conditions such as asthma, heart failure or diabetes
• Ear infections and, in children, fits caused by fever
• Dehydration, particularly in young children and frail older adults
• Rarely, inflammation of the heart, brain or muscles
• Hospital admission, and in the most severe cases flu can be life-threatening

Long-term outlook

The outlook is good for most people. Flu usually improves over about a week, with a cough and tiredness that fade over the following week or two. Vaccination gives you the best chance of a milder illness if you do catch flu, and it also helps protect the people around you who are more vulnerable. If you are offered the vaccine, taking it is a simple, low-risk step that many people find reassuring year after year.

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