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.
Seasonal influenza (flu) vaccine
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 strains of flu virus that are most likely to cause outbreaks in the coming winter. Each year these are slightly different, so a new jab needs to be made every year. You need a yearly jab to stay protected.
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. For the 2018/19 flu season in the UK it is recommended that quadrivalent (four-part) vaccines contain the following:
- An A/Michigan/45/2015 (H1N1)pdm09-like virus.
- An A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus.
- An B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage).
- A B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage).
It is recommended that the influenza B virus component of trivalent (three-part) vaccines is the B/Colorado/06/2017-like virus, as above.
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.
Those aged 18-65 years at increased risk of flu should be offered the quadrivalent vaccine, which protects against four strains of flu.
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.
Who should be immunised against the seasonal flu virus?
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. Current advice is that you should be immunised against the seasonal flu virus each autumn if you:
- Are aged 65 years or over.
- 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 poor 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 have had a stroke in the past.
- Live in a nursing home or other long-stay residential care accommodation.
In addition to the main at-risk groups of people listed above:
- You should be immunised if you are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill with flu.
- Staff involved in direct patient care (including nursing and care homes) may be offered a flu jab by their employer.
- Pregnant women. Even if you are otherwise healthy it is now recommended that all pregnant women receive the flu jab.
- Healthy children - see below.
If you are healthy and an adult aged under 65 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 and the flu jab
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.
In the 2018/19 flu season, flu vaccine should also be offered to all children who are 2-9 years old (but not 10 years or older) on 31 August 2018 and to all primary school-aged children in former primary school pilot areas. This is different from previous years because:
Reception Year children (aged 4-5 years) will now be offered flu vaccination in their reception class, rather than at their general practice surgery.
Children in School Year 5 will be included in the programme this year, as part of the planned extension of the children's programme.
Pregnant women and the flu jab
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.
Seasonal flu shot side-effects
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.
Who should not have the seasonal flu jab?
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.
Where can I have the flu jab?
You can be given your flu jab from one of the following:
- Your GP surgery.
- 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
Influenza: the Green Book, Chapter 19; Public Health England (August 2015)
PHE guidance on use of antiviral agents for the treatment and prophylaxis of seasonal influenza; Public Health England (October 2018)
Immunizations - seasonal influenza; NICE CKS, May 2018 (UK access only)
Rondy M, Larrauri A, Casado I, et al; 2015/16 seasonal vaccine effectiveness against hospitalisation with influenza A(H1N1)pdm09 and B among elderly people in Europe: results from the I-MOVE+ project. Euro Surveill. 2017 Jul 2722(30). pii: 30580. doi: 10.2807/1560-7917.ES.2017.22.30.30580.