Fluenz (Influenza vaccine)

How does it work?

Fluenz nasal spray is a vaccine against seasonal flu (influenza) that contains a live but weakened form of the flu virus. It works by provoking the body's immune response to the flu virus, without actually causing the illness.

When the body is exposed to foreign organisms, such as viruses and bacteria, the immune system produces antibodies against them. Antibodies help the body recognise and kill the foreign organisms. They then remain in the body to help protect the body against future infections with the same organism. This is known as active immunity.

The immune system produces different antibodies for each foreign organism it encounters. This establishes a pool of antibodies that helps protect the body from various different diseases.

Vaccines contain extracts or inactivated forms of bacteria or viruses that cause disease. These altered forms of the organisms stimulate the immune system to produce antibodies against them, but don't actually cause disease themselves. The antibodies produced remain in the body so that if the organism is encountered naturally, the immune system can recognise it and attack it, thus preventing it from causing disease.

Each virus or bacteria stimulates the immune system to produce a specific type of antibody. This means that different vaccines are needed to prevent different diseases.

Influenza vaccines stimulate the immune system to produce antibodies against the virus that causes flu. The flu virus, however, is constantly changing its structure (mutating). This means that each year a different vaccine containing different strains of the virus is needed. All brands of this year's flu vaccine contain three different strains of the flu virus that have been identified by the World Health Organisation and the EU as being prevalent for the 2013 to 2014 season. These are an H1N1 strain of influenza A, an H3N2 strain of influenza A and a strain of influenza B.

Influenza vaccination should be repeated each year with the appropriate, approved vaccine. Protection against flu usually occurs within two to three weeks after vaccination, and the length of the protection varies, but usually lasts 6 to 12 months.

What is it used for?

  • Preventing seasonal flu (influenza) in children aged 2 to 18 years.

The Fluenz vaccine has been shown to provide greater protection against flu in children aged 2 to 18 years than injectable flu vaccines containing inactivated virus.

A yearly flu vaccine is recommended for people who run an increased risk of complications, such as pneumonia or being admitted to hospital, if they get flu.

The Fluenz vaccine is an option for children and adolescents who need a flu vaccine because they fall into a risk group. These include those living in long-stay residential care homes and those with one or more of the following conditions: chronic lung disease, including asthma; chronic kidney, liver, heart or neurological disease; or diabetes.

In July 2012 the Department of Health recommended that children aged 2 to 17 years who are otherwise healthy should also be included in the flu vaccination programme. This is in order to protect healthy children from flu, but also to help reduce the spread of flu and thus protect many others, such as younger siblings, grandparents and those in the at risk groups. Fluenz will be the vaccine used for this programme.

The programme begins in September 2013, when all children who are aged two or three years on the 1st September 2013 will be offered the flu vaccine by their GP. In some parts of the country primary school children aged 4 to 11 years will also be offered the vaccine. These pilots in primary school children are to help establish what will be the most efficient way of giving the vaccine to all children each year. The programme will then gradually be extended each year to include all children up to 16 years of age.

Children under two years of age aren't included in the programme because Fluenz was shown to cause wheezing in this younger age group. Babies are also likely to be protected indirectly by protecting older children. Children aged between six months and two years who have any of the long-term health conditions listed above will continue to be offered an annual injectable flu vaccine.

How is it given?

  • The Fluenz vaccine will be given by a doctor, nurse or pharmacist. It is administered as a nasal spray, not as an injection.
  • The vaccine is given using a single-use nasal applicator, which contains two doses – one for each nostril.
  • The nasal applicator will be inserted just inside the child’s nostril while they are sitting in an upright position and breathing normally. One 0.1ml dose is sprayed into each nostril. The child doesn’t need to sniff or breathe in the vaccine.
  • If the child sneezes or blows their nose after having the vaccine there is no need for it to be given again.
  • Children aged two to nine years who have not previously been vaccinated against flu should be given a second dose of the vaccine (one spray in each nostril) four weeks after their first vaccination.
  • The vaccine should be repeated each year before the start of the flu season. (The best time to have it is from September to early November.)


  • This vaccine will only protect against flu caused by the strains of the influenza virus that are closely related to those found in the vaccine. It will not prevent flu-like illnesses caused by other germs.
  • This vaccine contains live but weakened strains of the influenza virus. It can’t cause flu in children given the vaccine or in people with a healthy immune system. However, there is a chance that the virus in the vaccine could cause infection if it was transmitted to someone who has a very underactive immune system. For this reason, children and adolescents who have had this vaccine should avoid close contact with people who are severely immunocompromised (for example people who have had a bone marrow transplant) for one to two weeks after having the vaccine. Children who live with someone who is severely immunocompromised and thus can’t avoid close contact should be given a different flu vaccine.

Not to be used in

  • Children with feverish illness or infection, or a heavily blocked or runny nose. (The vaccine should preferably be postponed until after recovery).
  • Children who have a serious allergy to eggs or chicken protein, or to the antibiotic gentamicin.
  • Children who have an underactive immune system, for example due to a genetic defect, disease such as leukaemia or lymphoma, or treatment with immunosuppressant medicines such as chemotherapy, high-dose corticosteroids, or immunosuppressants, eg used following an organ transplant.
  • Children with symptomatic HIV infection.
  • Children with severe asthma or wheezing.
  • Children taking medicines containing salicylate medicines such as aspirin.
  • This vaccine is not recommended for children under two years of age because it was shown in clinical trials to cause wheezing in this younger age group.
  • This vaccine is not recommended for adults aged 18 years and over because studies have suggested that it is less effective than injected flu vaccines in adults.

This vaccine should not be used if your child is allergic to any of its ingredients. Please inform your doctor or pharmacist if your child has previously experienced such an allergy. If you feel your child has experienced an allergic reaction after having this vaccine, inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain vaccines should not be used during pregnancy or breastfeeding. However, other vaccines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before having any vaccine.

  • The safety of the Fluenz vaccine for use during pregnancy has not been studied. it is not recommended for young women who are pregnant. Other flu vaccines that are given by injection are suitable for pregnant women and are recommended for protecting pregnant women against flu – see the factsheets linked at the end of this page for more information or ask your doctor for further information and advice.
  • It is not known if the virus in Fluenz passes into breast milk. It should not be given to young mothers who are breastfeeding. There are injectable flu vaccines available that can be given to women who are breastfeeding. Ask your doctor for further advice.

Side effects

Vaccines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this vacccine. Just because a side effect is stated here does not mean that all people having this vaccine will experience that or any side effect.

Very common (affect more than 1 in 10 people)

  • Blocked or runny nose.
  • Decreased appetite.
  • Headache.
  • Feeling generally unwell.

Common (affect between 1 in 10 and 1 in 100 people)

  • Aching muscles (myalgia).
  • Fever.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

  • Nosebleeds.
  • Rash.
  • Hypersensitivity reactions such swelling of the face or tongue, shortness of breath or itchy skin rash.

The side effects listed above may not include all of the side effects reported by the vaccine's manufacturer.

For more information about any other possible risks associated with this vaccine, please read the information provided with the vaccine or consult your doctor or pharmacist.

How can this vaccine affect other medicines?

It is important to tell the person administering this vaccine if your child is taking any medicines.

This vaccine must not be given to people whose immune system is underactive as a result of treatment with immunosuppressant medicines, because the vaccine could cause serious infection in these people. Immunosuppressant medicines include those listed below:

  • chemotherapy for cancer (this vaccine should be not be given until at least six months after the last chemotherapy dose)
  • generalised radiotherapy for cancer (this vaccine should be not be given until at least six months after the last radiotherapy dose)
  • high-dose corticosteroids, eg prednisolone (this vaccine should not be given until at least three months after stopping treatment with high doses of corticosteroids taken by mouth or injection)
  • immunosuppressants used to prevent rejection of organ transplants, eg azathioprine, ciclosporin, mycophenolate, tacrolimus (this vaccine should not be given until at least 12 months after stopping treatment)
  • other medicines that suppress the activity of the immune system, eg abatacept, adalimumab, anakinra, efalizumab, etanercept, infliximab, leflunomide.

This vaccine should not be given to a child who is taking any salicylate-containing medicines, eg aspirin or aspirin-containing medicines. This is because there is a very small risk of a condition called Reye’s syndrome, which affects the brain and liver developing. Aspirin and aspirin-containing medicines should not be given to children under 18 years old for at least four weeks after the vaccine and then only if prescribed by a doctor.

Antiviral medicines that are used to treat flu, such as oseltamivir and zanamivir, may reduce the effectiveness of the Fluenz vaccine. The vaccine should not be given for at least two days after finishing a course of treatment with one of these medicines. If treatment with oseltamivir or zanamivir is needed in the two weeks after having the Fluenz vaccine they are likely to make the vaccine less effective and another dose may be needed.

Other flu vaccines

  • Agrippal .
  • Enzira.
  • Fluarix.
  • Fluvirin.
  • Imuvac .
  • Inflexal V.
  • Influvac.
  • Intanza.
  • Optaflu.
  • Viroflu.