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. 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 (including children 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 2015-16 season, over 11 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. 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.)

Each year the nasal flu spray protects against four of the flu strains which are most likely to be around. It prevents 50% - 60% of flu cases. 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. 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 in the programmes in England, Wales, Scotland and Northern Ireland.

In the 2017-18 season the nasal flu spray will be available to the following groups:

  • All children aged 2, 3 or 4 on August 31 2017
  • All children in school years 1, 2, 3 and 4 in the UK. Children in school years 5 and 6 will also be offered the vaccine in Scotland, Northern Ireland and other areas of the UK which ran pilot 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

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.

The nasal flu spray has been shown to work well in young people (better than the inactivated flu vaccine) and has a good safety profile. It has been used widely in the United States for about a decade; millions of doses have been given.

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. However 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.

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, the advice is that the nasal flu vaccine can safely be given to most children with egg allergy (see 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.

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.


The viruses used in the 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 2016/17 season .

The vaccine also contains gelatine, used as a stabiliser. See more information on gelatine in vaccines. The gelatine comes from pigs, but very sensitive scientific tests have shown that no DNA from pigs can be detected in the nasal flu spray. These tests show that the gelatine is broken down so much that the original source cannot be identified.

The vaccine may contain a trace of gentamicin, an antibiotic used in the manufacturing process. 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 grown in the laboratory using animal cell-lines. See more information on animal cell-lines.

Other ingredients present in very small amounts:

The nasal flu spray does not contain the preservative thiomersal (mercury).

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.

See more information on the monitoring of vaccine safety.

More information about the vaccine

Common myths about flu and the flu vaccine

'Flu isn't serious, so my child doesn't need a flu vaccine' and 'My children never get ill, so they don't need the vaccine'

It is tempting to think that flu is no worse than a bad cold, but in fact it is a serious disease which can infect anyone. For people at risk of complications, flu can lead to hospitalisation or even death. In rare cases flu can kill otherwise healthy people. 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 will help to reduce the spread of the disease, and so reduce the chance of passing on the flu virus to other people who may be at risk of flu.

'Last year my children had the flu vaccine but they got ill anyway, so it doesn't work'

No vaccine is 100% effective, including the flu vaccine. However, the vaccine usually prevents about half of all flu cases. For people who get flu after being vaccinated, the disease is often less severe than it would have been. It is important to remember that the flu vaccine only protects against flu, but there are other illnesses which have flu-like symptoms which you can still catch after getting the flu vaccine. It takes up to two weeks for the vaccine to take effect, so you could still catch flu if you are exposed to the virus during this time. Getting vaccinated as early as possible in the season can help to prevent this.

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 16 different types of the H protein, and 9 different types of the N protein. This means there are 144 different possibly varieties of Influenza A – from H1N1 (the Swine Flu virus) to H16N9. Not all of these types are known to infect humans, but there are still a lot of possible 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 occasionally the flu vaccine may not be a good match for all the strains of flu that are circulating.

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?

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.

Page last updated: 
Tuesday, April 18, 2017


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