Flu vaccine (Nasal)

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Influenza (flu) is a very common and highly infectious disease caused by a virus. It is much more severe than the common cold and results in at least 2-3 days in bed, leading to missed work and school days. For some at-risk groups, flu can be very dangerous. Flu complications lead to tens of thousands of hospital stays and an average of 600 deaths in the UK every year.

This page provides information about:

  • Key facts about the live attenuated influenza vaccine (LAIV)
  • Who is eligible and how to get the vaccine?
  • How effective is the NHS flu immunisation programme?
  • The story of Brittney Peters – losing a child to flu
  • Why do we need the flu vaccine every year?
  • Safety and side effects
  • Ingredients


In the 2020-21 season, over three million children were vaccinated against flu across the UK.

The flu vaccine for children is a nasal spray (sprayed into the nose), not an injection. The live attenuated influenza vaccine (LAIV) contains live forms of flu virus which have been weakened (attenuated). These stimulate the immune system but do not cause disease in healthy people. It can safely be given at the same time as all other routine childhood vaccines, including other live vaccines. However, the nasal flu vaccine should not be given to people who are clinically immunosuppressed (see below). 

The brand name of the nasal flu spray used in the UK is Fluenz Tetra (see the Patient Information Leaflet). In the US the same vaccine is called FluMist.

It is recommended to get the flu vaccine in the autumn, before outbreaks of flu have started.


The UK is gradually introducing annual flu vaccination for all children. There are some differences between the programmes in England, Wales, Scotland and Northern Ireland. The programme may be extended to additional secondary school years once there has been an assessment of the full impact of the current school programme. In the 2021-22 season, the programme was extended to all children from year 7 - 11 in secondary school, however for the 2022-23 season, this cohort of children will not be eligible. The programme will however, continue to vaccinate all primary school children and those aged 2 to 4 years

In the 2022-23 season the nasal flu spray will be available for free to the following groups:

  • All children aged 2 or 3 on 31st August 2022 (offered through their GP surgery)
  • All children in Primary school (reception class to year 6)
  • Children and young people aged 2 to 17 who are 'at risk' of developing complications from flu, such as those with long-term health conditions including:
    • Respiratory (lung) diseases, including asthma
    • Heart disease, kidney disease or liver disease
    • Neurological (brain or nerve) conditions including learning disability
    • Diabetes (see a short film of a woman with Type 1 diabetes talking about why she gets the flu vaccine)
    • A severely weakened immune system (immunosuppression), a missing spleen, sickle cell anaemia or coeliac disease
    • Being seriously overweight (BMI of 40 and above)

Some cohorts that were eligible in the 2021 to 2022 season are not eligible for the 2022 to 2023 season. This includes:

  • Secondary school children in Years 7 to 11 (between 11 and 15 years of age on 31 August 2022)


If a child has missed the flu vaccine in school, they can also receive the vaccine from their GP surgery.

Children between 6 months and 2 years old with long-term health conditions will be offered an injection flu vaccine instead of the nasal spray (see inactivated flu vaccine). Babies under 6 months old are too young to receive a flu vaccine. Flu vaccination is offered to all pregnant women in the UK (see Vaccines in Pregnancy: Flu). As well as protecting pregnant women themselves, this also helps to protect their newborn babies from flu.

Your doctor may recommend the flu vaccine in other circumstances as well.


The flu vaccine works better in some years than others (see ‘Why do we need the flu vaccine every year?’ below). In children aged 2-17, the flu vaccine prevented 66% of flu cases in 2016-17, 27% of flu cases in 2017-18, 49% of flu cases in 2018-19 and 45% of flu cases in 2019-20 (see research by Public Health England on the effectiveness of flu vaccines in the 2016-17 season2017-2018 season2018-19 season and 2019-20 season).

nasal flu vaccine effectiveness 20 21

Click here for an accessible text version of this graph

The aim is to protect children and also people around them, particularly those at risk of complications of flu. If children get flu they can remain infectious for longer than adults (up to two weeks), and they are also more likely to pass on the infection. There is good evidence to show that vaccinating children against flu is a good way to reduce flu-related illness, GP visits, hospital admissions and deaths for the whole community. 

Overall, since the programme began, the impact of the nasal flu vaccine has been greatest in pilot areas of the UK where children in all primary school years have been offered vaccination. This includes the whole of Scotland and Northern Ireland. In 2015 Public Health England published a study evaluating the impact of these flu vaccination pilot programmes in 2014-15 . The study showed that the programme in the pilot areas had a significant impact on flu in children and the community as a whole. 

As well as offering the nasal flu vaccine to all primary school children, Scotland and Northern Ireland had higher rates of vaccine uptake than England.

The Story of Brittney Peters


Click here for an accessible text version of this video


Side effects associated with the vaccine are:

Very common (affecting more than 1 in 10 people)

  • runny or stuffy nose
  • loss of appetite
  • feeling generally unwell
  • headache

Common (affecting up to 1 in 10 people):

  • high temperature (fever)
  • aching muscles

Uncommon (affecting up to 1 in 100 people):

  • nose bleeds (it is thought these are unlikely to be caused by the vaccine itself)
  • rash
  • allergic reactions

Additional information about vaccine side effects, anaphylaxis and adverse reactions can be found here.

There is no evidence that healthy unvaccinated people can catch flu from the nasal flu spray (either from airborne spray droplets in the room where the vaccine is given, or from vaccinated individuals ‘shedding’ the virus). 

It is known that vaccinated children shed the virus for a few days after vaccination (through sneezing or coughing). However, the vaccine virus is weakened, and so it is much less able to spread from person to person than flu viruses that circulate during the flu season, and it cannot grow inside the body. The amount of virus that children shed is normally below the levels needed to pass on infection to others. The virus does not survive for long outside the body.

It is therefore not necessary for children to be excluded from school during the period when the vaccine is being given. The only exception is the very small number of children who are extremely immunocompromised (for example, those who have just had a bone marrow transplant). These children are usually advised not to attend school anyway, because of the higher risk of being in contact with infections that circulate in schools.

The nasal flu spray should not be given to anyone who is severely immunodeficient (so that their immune system cannot control viral infections in the normal way) due to a medical condition or treatment with an immunosuppressive therapy such as:

  • Acute and chronic leukaemias while on chemotherapy
  • Lymphoma while on chemotherapy
  • Immunosuppressed individuals with HIV infection whose immune system is compromised, usually because they are not on highly active antiretroviral therapy (HAART)
  • Individuals with inheritated cellular immune deficiencies
  • Individuals on high dose corticosteroids (prednisolone at least 2mg/kg/day for a week or 1mg/kg/day for a month or equivalent) 
  • Individuals on other immunosuppressive drugs, including some monoclonal antibodies

This is because the weakened viruses in the vaccine could replicate too much and cause infection. 

Children who have been vaccinated with the nasal spray should avoid close contact with people who have very severely weakened immune systems (for example, bone marrow transplant patients requiring isolation in a protective environment) for about two weeks following vaccination. If it is not possible for a child to avoid contact with someone who is severely immunosuppressed (for example, because they live in the same house), the child should not receive the nasal flu vaccine. It may be possible for them to have the inactivated flu vaccine instead.


Children need one dose of the vaccine every year. The exception is children who are in a clinical risk group, have not had a flu vaccine before and are under 9 years of age. These children need two doses of vaccine at least 4 weeks apart. Bristol Children's Vaccine Centre has a short video showing how the nasal flu vaccine is given.

Flu vaccines have an excellent safety record. They are the best protection we have against an unpredictable virus which can cause severe illness and deaths each year among at-risk groups. It is important to have a flu vaccine every year because the flu virus is very variable and changes over time. Each year there are different strains around, and a new vaccine has to be prepared to deal with them. Vaccination from previous years is not likely to protect people against current strains of flu. 

why is it difficult to make flu vaccines

Click here for an accessible text version of this infographic

Each year’s flu vaccine is made to give the best protection against the strains of flu that are expected to circulate in the coming season. The inactivated trivalent vaccine protects against three of the flu virus strains and the inactivated quadrivalent vaccine protects against four of the flu strains which are most likely to be around. The nasal flu vaccine is a quadrivalent vaccine, which protects against four flu virus strains.  


The nasal flu spray used in the UK is called Fluenz Tetra (also called FluMist in the US). Apart from the active ingredients (the antigens), it contains very small amounts of these added ingredients:

  • a small amount of highly purified gelatine, used as a stabiliser.
  • small amounts of amino acids called arginine hydrochloride and monosodium glutamate, both used as stabilisers. (Amino acids are the building blocks of proteins.)
  • sucrose (sugar), also used as a stabiliser

For the 2019/20 flu season, children whose parents refuse the LAIV flu vaccine due to the porcine gelatine content will be offered the inactivated flu vaccine as an alternative. 

The vaccine may also contain traces of these products used during the manufacturing process:

Growing the active ingredients for the vaccine:

The vaccine may contain very small amounts of egg proteins (ovalbumin) because the flu viruses are grown on hens' eggs. The Joint Committee on Vaccination and Immunisation has advised that most children with an egg allergy can be safely vaccinated with the nasal flu spray. This is because the ovalbumin content is very low. Public Health England produce an information sheet each year showing the ovalbumin content of flu vaccines in the current flu season.

The only exception is children who have a history of severe anaphylaxis to eggs which has previously needed treatment in intensive care. These children should be referred to specialists for immunisation in hospital. This advice is based on studies called SNIFFLE 1 and SNIFFLE 2 which tested the nasal flu spray on several hundred children with egg allergy. 

SNIFFLE 4 assessed the use of the nasal flu vaccine in children with severe asthma. A recent update from the Joint Committee on Vaccination and Immunisation advised that children receiving high-dose inhaled corticosteroid steroids can safely be given the nasal flu spray, but those with active wheezing in the last 72 hours or severe asthma which has required intensive care should not be given the vaccine. 


The nasal flu spray has also been used widely in the US since 2007 in children from the age of 2 upwards. It has a good safety profile. In 2016, research from the US showed that the nasal flu vaccine was no longer working well in children against one of the strains in the vaccine (influenza A(H1N1)). As a result the nasal flu spray was not recommended for use in the US during the 2016-17 and 2017-18 flu seasons (see our blog piece from September 2016). 

However, research in the UK and in Finland showed that in these two countries the nasal flu spray was still working well against influenza A(H1N1). It is not known why there is a difference between the US research and the UK and Finnish research, but the UK is continuing to monitor this. There is a review from August 2017 which looks at the issues in more detail.

For 2018-19 and 2019-20 seasons the vaccine manufacturers have used a different version of the influenza A(H1N1) strain in the vaccine. This is expected to be more effective against influenza A(H1N1), and the Centers for Disease Control and Prevention in the US are now once again recommending the nasal flu spray for use in children in the 2018-19 flu season.


Page last updated Wednesday, May 25, 2022