Immunisation for Flu Flu Jab

Authored by , Reviewed by Dr Hayley Willacy | Last edited | Meets Patient’s editorial guidelines

Flu jabs (or flu shots) do not prevent other viral infections which can cause coughs and colds, just the particular flu virus that is expected in the coming winter.

Flu immunisation (the flu jab) gives protection against seasonal flu and lasts for one year. If 10 people have the flu jab, it usually provides protection from flu for 7 or 8 of them. If the vaccine does not match the predicted flu types around that year, the protection rate can be lower. For example, in winter 2015/2016 the vaccine protected between 5-6 elderly people out of 10.

The immunisation is normally given in October or November each year. The flu injection is made from the three or four strains of flu virus that are most likely to cause outbreaks in the coming winter. A vaccine which protects against four strains is called a quadrivalent vaccine; if it protects against three strains, it is called a trivalent vaccine.

Each year these are slightly different, so a new jab needs to be made every year. You need a yearly jab to stay protected.

Are you eligible for a free NHS flu vaccination?

You may be entitled to a free NHS flu vaccination from your GP or local pharmacist. Find out if you are eligible today.

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The World Health Organization (WHO) monitors influenza viruses throughout the world and recommends which strains are to be included in the current year's vaccine.

This year national guidance recommends that:

  • Everyone over 65 should be offered an adjuvanted trivalent vaccine. This vaccine protects against three strains of flu, but the way it is prepared means that it also boosts the immune response. This is important because people over 65 years old naturally don't respond as well to vaccines. Over-75s in particular are likely to get better protection from the adjuvanted form. You may be offered a quadrivalent vaccine if the trivalent vaccine is not available.
  • Those aged 18-65 years at increased risk of flu should be offered the quadrivalent vaccine, which protects against four strains of flu.
  • Children aged 2-18 should be offered a quadrivalent nasal spray version of the vaccine. If there is a medical reason they cannot have this and they are in a medical at-risk group, they can be offered the quadrivalent vaccine.

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.

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 to give full protection after having the jab.

The Department of Health 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.

Because of concerns that a combination of flu and COVID-19 might increase the risk of serious complications from either infection, the NHS flu vaccination programme has been expanded in 2020-2021.

For the 2020-21 flu season, you are eligible for NHS flu vaccination if you:

  • Are aged 65 years or over.
  • Were advised by the NHS to 'shield' in the first half of 2020 because you are in a clinically extremely vulnerable group.
  • Live with someone who was advised to shield.
  • 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 weakened 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 Parkinson's disease or have had a stroke in the past.
  • Live in a nursing home or other long-stay residential care accommodation.
  • Have a learning disability.

In addition to the main at-risk groups of people listed above you are eligible for an NHS vaccine if you:

  • Are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill with flu.
  • Are in regular close contact with someone who has a weakened immune system.
  • Are employed by a registered residential care/nursing home.
  • Are employed by a voluntary managed hospice provider.
  • Are employed through Direct Payments (personal budgets) and/or Personal Health Budgets, such as Personal Assistants, to deliver home care to patients and service users
  • Are pregnant. Even if you are otherwise healthy it is now recommended that all pregnant women receive the flu jab.


  • All healthy children aged 2-11 on 31 August 2020 will be offered the vaccine - see below.
  • Frontline health and social care workers who have direct patient contact should be eligible for a flu vaccination through their employer.
  • People aged 50-64 years old on or before 31 March 2021 may be eligible for NHS flu vaccination this year, but not at the start of the flu vaccination season. Depending on national vaccine supply, they may be contacted by their practice about getting a vaccination from November or December.

If you are healthy and an adult aged under 50 years 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.

Healthy children are offered immunisation through a nasal spray, rather than an injection. Immunising your child will protect them but also cut the risk of them passing on the infection to other vulnerable members of the family.

This vaccine is a 'live attenuated vaccine'. That means it contains live rather than dead virus, but the viruses have been weakened so they cannot multiply in the lungs, causing serious illness.

In the 2020/21 flu season, flu vaccine should also be offered to all children who are 2-11 years old (but not 12 years or older) on 31 August 2020:

  • Children aged 2-3 years old should be offered the vaccine through their GP practice.
  • Children in primary school and the first year of secondary school should be offered the vaccine through their school.

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. Having flu when you are pregnant may also be associated with serious pregnancy problems, prematurity and lower birth weight for the baby. Your GP (or possibly midwife) should offer you a flu vaccination during your pregnancy, if it runs over the winter. If they don't, do ask for one.

There are no known problems from giving the seasonal flu jab to women who are pregnant.

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 are given the vaccine (Fluenz Tetra®) 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.

The vast majority of people can receive flu immunisation (the flu jab). However, the following groups of people should not be immunised with the usual vaccine:

  • Those who have a severe allergy to eggs. However, you can still receive a different immunisation that protects against the swine flu strain (H1N1v). There is also egg-free vaccine - see below.
  • Those who have had a previous allergic reaction to a flu virus immunisation.

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.

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 breastfeeding.

What if I have an egg allergy?

Routine vaccine should not be given where there is a confirmed severe allergic reaction to egg products, as the vaccines are prepared in hens' eggs. It has now been advised that, except for those with severe anaphylaxis to egg (they have previously required intensive care as a result), children with an egg allergy can be safely vaccinated with Fluenz Tetra®. An egg-free vaccine is also available and can be given.

Inactivated influenza vaccines that are egg-free (or have a very low ovalbumin content) are available and it has been shown that they may be used safely in individuals with egg allergy. Since 2016 the ovalbumin content of live attenuated influenza vaccine (LAIV) has been reduced to ≤0.12 micrograms/ml. The ovalbumin content of influenza vaccines will be published prior to the influenza season.

You can be given your flu jab from one of the following:

  • Your GP practice, or a clinic set up by them in conjunction with other local practices.
  • Your local pharmacy (if they offer this service).
  • Your midwife (if they offer it for pregnant women).

Note: if you have the vaccination somewhere other than your GP surgery, they should notify your GP on your behalf.

Further reading and references