Immunisation against seasonal flu (the flu jab) is given every year to people at risk of developing serious complications from seasonal influenza (flu). People who are recommended to receive the flu jab are listed below. If you have the flu jab you greatly reduce your chance of getting seasonal flu.
What is influenza?
Influenza (flu) is an illness caused by the flu virus. There are different strains of flu virus. Flu is passed from person to person through droplets created when someone with the infection sneezes or coughs. You can also catch it by touching a surface where the virus has been deposited. Flu can spread quickly in these ways.
Symptoms of flu include a high temperature (fever), muscle aches, cough, headache and extreme tiredness. Flu usually lasts for between two and seven days. Most people recover fully. Complications such as a chest infection or pneumonia develop sometimes.
Complications are more common in young babies, older people, people with an underlying disease (especially heart or lung diseases), pregnant women and people who have a weak immune system. Complications are sometimes serious and a number of people die each year in the UK. These are usually elderly.
There are three types of flu virus - A, B and C. Influenza types A and B cause most of the cases of flu. Each winter a different strain of the flu virus causes an outbreak which affects many people. This is called seasonal flu. During an outbreak of seasonal flu, if you get a flu-like illness, it is more likely to be caused by the prevailing flu virus than by any other. Most cases of flu usually occur in a period of six to eight weeks during the winter.
Swine flu is caused by a particular strain of influenza A virus which is called H1N1v. It seems to affect children and young adults more commonly than those over the age of 60 years. Most people with this type of influenza have a mild flu-like illness. You are more likely to have sickness and/or diarrhoea with this type of flu.
Note: bird flu (avian influenza) is different and is more serious.
Immunisation against seasonal flu
Flu immunisation (the flu jab) gives excellent protection against seasonal flu and lasts for one year. If 10 people have the flu jab, it will provide protection from flu for 7 or 8 of them.
The immunisation is normally given in October or November each year. It is made from the strain of flu virus that is expected in the coming winter. Each year this is slightly different, so a new jab needs to be made every year. You need a yearly jab to stay protected.
Flu jabs do not prevent other viral infections which can cause coughs, colds and flu-like illnesses. It protects only against the particular flu virus that is expected in the coming winter.
The adult immunisation does not actually contain any living flu virus. This means that it cannot cause flu or any other infections. If you develop a cough or cold shortly after having a flu immunisation it is a coincidence.
Who should be immunised against the seasonal flu virus?
Seasonal flu is the particular type of flu virus that arrives in the UK each autumn. The actual type varies from year to year. The new jab is developed each year to protect against the expected type. The flu jab takes up to 14 days for full protection after having the jab.
The Department of Health (DH) issues advice as to who should be immunised. This is reviewed from time to time. The aim is to protect people who are more likely to develop complications from flu. Current advice is that you should be immunised against the seasonal flu virus each autumn if you:
- Are aged 65 or over.
- Have any ongoing (chronic) lung diseases.
Examples include chronic bronchitis, emphysema, cystic fibrosis and severe asthma (needing regular steroid inhalers or tablets). It is also recommended for any child who has previously been admitted to hospital with a chest infection.
- Have a chronic heart disease.
Examples include angina, heart failure or if you have ever had a heart attack.
- Have a serious kidney disease.
Examples include nephrotic syndrome, chronic kidney disease, a kidney transplant.
- Have a serious liver disease such as cirrhosis.
- Have diabetes.
- Have a poor immune system.
Examples include if you are receiving chemotherapy or steroid treatment (for more than a month), if you have HIV/AIDS or if you have had your spleen removed.
- Have certain serious diseases of the nervous system such as multiple sclerosis or have had a stroke in the past.
- Live in a nursing home or other long-stay residential care accommodation.
In addition to the main at-risk groups of people listed above:
- You should be immunised if you are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill with flu.
- Staff involved in direct patient care (including nursing and care homes) may be offered a flu jab by their employer.
- Pregnant women. Even if you are otherwise healthy it is now recommended that all pregnant women receive the flu jab.
If you are healthy and an adult aged under 65 and you do not fall into any of the above categories, then you do not need immunisation against seasonal flu. This is because you are unlikely to develop complications from flu.
In the 2015/16 flu season, flu vaccine should be offered to all children who are 2, 3 and 4 years old on 31 August 2015 and to all children of school years 1 and 2 age.
Why do pregnant women need to have the flu jab?
Pregnant women are at increased risk of developing a more severe illness. They are also more likely than non-pregnant women to be admitted to hospital. There are no known problems from giving the seasonal flu jab to women who are pregnant.
Are there any side-effects from the seasonal flu jab?
Immunisation against seasonal influenza (the flu jab) usually causes no problems. You may have a temporary mild soreness at the injection site. Sometimes, it can cause a mild raised temperature (fever) and slight muscle aches for a day or so. This soon settles and does not lead to flu or other problems.
Serious reactions have been reported but are rare. For example, a severe allergic reaction, inflammation of nerves and inflammation of the brain (encephalitis) are very rare reactions.
Children will be given a different vaccine to adults. It is called Fluenz® and is given by nasal spray. It contains a live but weakened form of the flu virus. It will not cause flu in a healthy child. However, if a healthy child lives with someone who does not have a healthy immune system (for example, who has HIV or has had a bone marrow transplant), they should have the other (inactive) type of vaccine. The live, weak form of vaccine has been shown to be more effective in preventing flu in children.
Who should not have the seasonal flu jab?
The vast majority of people can receive flu immunisation (the flu jab). However, the following groups of people should not be immunised:
- Those who have a severe allergy to eggs. However, you can still receive a different immunisation that protects against the swine flu strain (H1N1v).
- Those who have had a previous allergic reaction to a flu virus immunisation in the past.
Children who do not have a good working immune system should not be given the live flu vaccine. This includes children with leukaemia or HIV. Children who live with, or have close contact with, someone who has a poorly working immune system should also not be given the live vaccine. However children who do not have a good working immune system and children who live with, or have close contact with, someone who has a poorly working immune system can be given the inactivated vaccine.
Although most flu vaccines are grown in hens' eggs, an egg-free vaccine is available and can be given. People with a history of severe egg allergy can be given the egg-free vaccine.
Flu immunisation can be given at the same time as other immunisation; it is often given at the same time as the pneumonia immunisation. It is also safe to be given if you are either pregnant or breast-feeding.
Further reading & references
- Flu Plan Winter 2015/16; Public Health England, Dept of Health, NHS England
- Which flu vaccine should you or your child have; NHS England (Winter 2014-15)
- Immunisation against infectious disease - the Green Book (latest edition); Public Health England
- Immunizations - seasonal influenza; NICE CKS, February 2015 (UK access only)
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Tim Kenny
Dr Colin Tidy
Prof Cathy Jackson