Nasal Flu Vaccine

General information on flu vaccines in the UK

Influenza (flu) is a very common and highly infectious disease caused by a virus. It can be very dangerous, leading to serious complications and death, especially for people in risk groups. In rare cases flu can kill people who are otherwise healthy. In the UK an average of 600 people a year die from complications of flu, but in some years this can rise to over 10,000 people. Flu leads to hundreds of thousands of GP visits and tens of thousands of hospital stays a year. Apart from protecting individual people, getting the flu vaccine helps to reduce the spread of the disease, and so reduces the chance of passing on the flu virus to other people who may be at risk of flu.

There are two different kinds of flu vaccine available in the UK, both of which protect against common strains of seasonal flu:

  • The nasal flu vaccine (this page) is offered each year to children over the age of two. The vaccine is being introduced gradually over a number of years.
  • The inactivated flu vaccine is recommended mainly for adults, but also for babies and children from 6 months to 2 years old who are at risk from complications of flu. This includes children under the age of 2 with long-term health conditions such as asthma and other lung diseases, liver or kidney disease, brain conditions and learning disabilities.

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.

In the 2017-18 season, more than 14 million adults and children in England got vaccinated against flu.

Key vaccine facts

The flu vaccine for children is a nasal spray (sprayed into the nose), not an injection. It can safely be given at the same time as all other routine childhood vaccines, including other live vaccines.

The vaccine contains live forms of flu virus which have been weakened (attenuated). These stimulate the immune system but do not cause disease in healthy people.

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.

Who should have the vaccine?

The UK is gradually introducing annual flu vaccination for all children. At the moment the focus is on rolling out the programme to all primary schools, and continuing to vaccinate children aged 2 to 4 years. There are some differences between the programmes in England, Wales, Scotland and Northern Ireland.

In the 2018-19 season the nasal flu spray will be available to the following groups:

  • All children aged 2 or 3 on August 31 2018
  • All children in Reception class and in school years 1, 2, 3, 4 and 5 in the UK. Children in school year 6 will also be offered the vaccine in Scotland, Northern Ireland and other areas of the UK which ran pilot flu vaccination programmes in previous years
  • Children aged 2 to 17 who are 'at risk' from flu, such as children with long-term health conditions

How many doses are needed?

Children need one dose of the vaccine each year, unless they are in a clinical risk group and have not had a flu vaccine before, in which case they need two doses of vaccine at least 4 weeks apart. ('Clinical risk groups' include children with long-term health conditions such as asthma and other lung diseases, liver or kidney disease, brain conditions and learning disabilities.) Bristol Children's Vaccine Centre has a short video showing how the nasal flu vaccine is given .

It is important to have a flu vaccine every year. This is 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. See Five good reasons to get the flu vaccine for more information about the annual flu vaccine and how it is prepared.

What protection does the vaccine give?

Each year the nasal flu spray protects against four of the flu strains which are most likely to be around. In the UK it has been shown to prevent 55% - 65% of flu cases in children. It is recommended to get the flu vaccine in the autumn, before outbreaks of flu have started.

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. The best results have been achieved in areas of the UK where all primary school age children are offered the vaccine, and where uptake of the vaccine is high. See 'Does the vaccine work?' at the bottom of this page.

Who should not have the vaccine?

The nasal flu spray should not be given to anyone who is very severely immunosuppressed. 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, people receiving chemotherapy or people who have just had an organ transplant) for about two weeks following vaccination. This is because there is a very small chance of passing the weakened vaccine virus on to them. (See also 'Is the vaccine safe?' at the bottom of this page.)

The vaccine is not recommended for children with severe asthma or active wheezing at the time of vaccination because of limited safety data in these groups. It is not licensed for children younger than two. Children aged from 6 months to 2 years who are at risk from complications of flu should be given the inactivated flu vaccine. However, evidence shows that the nasal flu vaccine can safely be given to most children with egg allergy (see the 'Ingredients' section below).

A heavily blocked or runny nose (rhinitis) might prevent the vaccine being delivered correctly, so vaccination should be delayed until this has cleared up. However, the dose does not need to be repeated if the patient sneezes or blows their nose after the vaccine is given.

Medicines containing aspirin (acetylsalicylic acid) should not be given to children for 4 weeks after the nasal flu vaccine. This is because of the risk of Reye’s syndrome, a very rare but serious disease that can affect the brain and liver.

Why the UK is recommending this vaccine

In the UK the nasal flu spray has worked well in young people since it was introduced in 2013. It was used for many years in the US and has a good safety profile. Research from 2016 showed that the nasal flu vaccine was no longer working well in children in the US, and for this reason the vaccine is no longer recommended for use in the US. However, research in the UK shows the opposite. In 2016-17, the nasal flu vaccine reduced the risk of flu by 66% in children (see the Public Health England report for 2016-17 ). The vaccine is also working well in Finland. It is not known why there is such a big difference between the US research and the UK and Finnish research, but the UK will continue to monitor this. There is a review from August 2017 which looks at the issues in more detail. See our blog piece from September 2016 on why the UK is still strongly recommending that children get the nasal flu vaccine. This recommendation has been repeated for 2018-19.


The nasal flu spray used in the UK is called Fluenz Tetra (also called FluMist in the US).

The viruses used in this vaccine are grown on hens' eggs and the vaccine may contain very small amounts of egg proteins (ovalbumin). Egg allergy is quite common in children under 5, and much more common in children than in adults. Around 60,000 children in the UK have egg allergies. The Joint Committee on Vaccination and Immunisation has now 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. 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. Public Health England have also produced an information sheet showing the ovalbumin content of flu vaccines in the 2017/18 season .

Fluenz Tetra also contains highly purified gelatine, used as a stabiliser. See more information on gelatine in vaccines.

The vaccine may contain a trace of gentamicin, an antibiotic used in the manufacturing process to stop bacteria growing and contaminating the vaccine. See more information on antibiotics in vaccines.

The viruses used to make the nasal flu spray are custom-made by putting together individual genes which have the right features to protect against this year's flu strains. This makes it the only vaccine in the UK schedule to contain GMOs. The virus strains are then produced in the laboratory using animal cell-lines before being grown on in hens' eggs. See more information on animal cell-lines.

Other ingredients present in very small amounts:

Side effects

Very common (may affect 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

Less common (affecting up to 1 in 100 people):

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

As with any vaccine, medicine or food, there is a very small chance of a severe allergic reaction (anaphylaxis). Anaphylaxis is different from less severe allergic reactions because it causes life-threatening breathing and/or circulation problems. It is always serious but can be treated with adrenaline. Depending on the cause of the reaction, and following expert guidance, the person may be able to have vaccinations in the future. The US Food and Drug Administration (FDA) carried out a very large study of 2.5 million people (children and adults) who received the nasal flu vaccine in 2003-2004 and 2004-2005. The study found that there were 7 reports of possible anaphylaxis following vaccination. This is a rate of about 1 in 360,000. During the SNIFFLE studies (see Ingredients section above) there were no reports of children with confirmed egg allergy having an anaphylactic reaction to the nasal flu vaccine.

Reactions listed under ‘possible side effects’ or ‘adverse events’ on vaccine product information sheets may not all be directly linked to the vaccine. See Vaccine side effects and adverse reactions for more information on why this is the case.

In the UK you can report suspected vaccine side effects to the Medicines and Healthcare products Regulatory Agency (MHRA) through the Yellow Card Scheme . You can also view data on Yellow Card reports for individual products . See more information on the Yellow Card scheme and monitoring of vaccine safety.

More information about the vaccine

The NHS has some useful leaflets about the flu vaccine, including one for children with learning disabilities .

This video made by Buckinghamshire County Council shows a mother taking her young son to get the nasal flu vaccine:

Why is it difficult to make flu vaccines?

Flu is a complicated virus. There are three basic types of flu: A, B and C. Type A is the most dangerous; it is the one that can cause serious disease and also triggers worldwide pandemics. Type C causes mild disease. Type B can make you feel very ill, but it has never led to a worldwide pandemic.

Type A is also much more complex than the other types of flu virus. On the surface of each Influenza A virus there are proteins that help the virus to invade cells. There are two kinds of protein: haemagglutinin and neuraminidase (referred to as H and N). There are 18 known different types of the H protein, and 11 known different types of the N protein. This means there are 198 different possible varieties of Influenza A – from H1N1 (the Swine Flu virus) to H18N11. Not all of these types are known to infect humans, but there are still a lot of options when it comes to designing the annual flu vaccine.

In addition, the flu virus can change quickly and easily. Each of the 144 types of Influenza A can undergo ‘antigenic drift’ – a process of genetic change that leads to even more variety within each type. Two different virus strains can even combine their genetic material to make a new sub-strain (this process is called ‘antigenic shift’, and is what led to the new Swine Flu virus in 2009).

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. However, decisions about what to put in the flu vaccine have to be made six months before the flu season starts. Every February in the Northern Hemisphere, the World Health Organization (WHO) reviews the types of flu that have been circulating in all parts of the world and chooses the ones which will go in the vaccine for the following autumn. This allows time for the vaccine to be made – but it also gives the flu virus time to change before vaccination starts in the autumn. In about 9 out of 10 years the vaccine matches the strains causing illness that winter, but sometimes the flu virus changes in ways that are not expected. This means that sometimes the flu vaccine may not be a good match for all the strains of flu that are circulating.

The viruses for flu vaccines are usually grown in hen’s eggs. This is a slow process, and can lead to something called ‘egg adaptation’. The flu virus strain starts to adapt to the conditions in the egg, leading to changes in the virus. This is another reason that the flu vaccine may not always match the circulating strains of flu.

Researchers are investigating ways to create a flu vaccine that protects against all the many different varieties of flu. If they are successful, it will mean that people will only need a single flu vaccine to give them lifelong protection, instead of getting a yearly vaccine. However, it will be several years before we find out if it will be possible to do this.

Does the vaccine work?

Since the nasal flu vaccine was introduced in 2013, Public Health England has been monitoring its effectiveness. The vaccine has been shown to prevent 55% - 65% of flu cases in children (see research by Public Health England on the effectiveness of flu vaccines in the 2015-16 season and in the 2016-17 season ).

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. Public Health England data from the 2015-16 flu season in the UK shows that, once again, there were much lower rates of 'flu-like illness' in Scotland and Northern Ireland in 2015-16 compared to the rest of the UK. As well as offering the nasal flu vaccine to all primary school children, Scotland and Northern Ireland had higher rates of vaccine uptake (over 70% of primary school children vaccinated) compared to England (just over 50% of children in years 1 and 2 vaccinated). The nasal flu vaccine programme is still being rolled out in England, and further information on the wider impact (especially on reducing flu cases and hospitalisations in older adults) is still awaited.

Research from the US appears to show that the nasal flu vaccine does not work well. Read our blog piece from September 2016 on why the UK is still strongly recommending that children get the nasal flu vaccine.

The infographic below shows the main impacts of the nasal flu programme in pilot areas where all primary school age children were vaccinated in 2014-15.

Is the vaccine safe?

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. 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.

As mentioned above, children who have been vaccinated with the nasal spray should avoid close contact with people who have very severely weakened immune systems (for example, people receiving chemotherapy or people who have just had an organ transplant) for about two weeks following vaccination. This is because there is a very small chance of passing the weakened vaccine virus on to them.

Page last updated: 
Thursday, June 28, 2018


Influenza (flu)

Influenza (flu) is a very common, highly infectious disease caused by a virus. It can be very... Read more