Flu vaccine and cancer treatment
Cancer or its treatment can lower your resistance to infection and make you more likely to catch flu. The flu 
makes it less likely that you will catch flu.
Flu (influenza) is an infection caused by a virus. It is very infectious. You mainly catch it from coughs and sneezes of people with the virus. The symptoms of flu often come on quickly and include:
- a high temperature (fever) or chills
- aching muscles
- a cough
- headaches
- extreme tiredness
Anyone who has flu feels quite unwell. But most healthy people recover within a few days as their immune system gets rid of the virus. Occasionally people develop complications, such as severe chest infections. These are serious illnesses which can need hospital treatment. A small number of people die due to complications.
Cancer and immunity
Cancer or its treatment can lower your resistance to infection. This is called immunosuppression or being . You may be more at risk of catching flu if this applies to you.
If you get flu and have low , you are more likely to become very ill. For example, you could develop a complication such as a chest infection (pneumonia).
The flu vaccination
The flu vaccination makes it less likely that you will catch flu. If you have had the vaccine and do get flu, there is a greater chance of a quicker recovery.
Adults have the vaccination as an injection into the muscle (intramuscular injection). Children usually have a spray vaccine through the nose (nasal). Some children might need to have it as an injection.
The flu virus changes each year. So, you need to have the vaccine again each year. This is to protect yourself against the most common type of flu predicted for that year.
Who should have the flu vaccination?
Some cancer treatments lower immunity and lower your resistance to flu. These include:
chemotherapy radiotherapy - some
targeted cancer drugs - some
immunotherapy treatments - long term
steroids - removal of the spleen - an organ in the body that is part of the
immune system
After cancer treatment, your resistance to infection might be low for some months or years.
Your GP or cancer specialist will usually recommend that you have the flu vaccine if one of these applies to you. Depending on your situation, they may suggest you continue with regular flu vaccines once your treatment has finished. But do check with them and ask when it is best to have it.
When to have the flu vaccination
Have the vaccination before the flu virus starts to circulate in the population. This is most likely to happen during the winter months. Flu season in the UK is usually between December and March.
New vaccines are developed each year and vaccination clinics usually start in late September and continue through to mid November. You can contact your GP to find out about clinic times. Or you might be able to have it at your local pharmacy. It is still worth having the vaccine after this time if you haven't had it.
When to have it if you are having cancer treatment
Cancer specialists generally recommend that you should have the flu vaccine before you start any cancer treatment. But this isn’t always possible.
For many cancer types, your specialist may advise you to have the vaccine during treatment if you haven’t had one. They will explain when it is best to have this. This might depend on different factors, such as the level of white blood cells in your blood. For example, with chemotherapy, you might have it towards the end of one and just before you start another cycle. The vaccine might not give you as much protection as it would a person whose immunity is not low. But it is still important for most people to have it.
Your specialist may recommend that you do not have a vaccine during treatment if you have a blood cancer. Cancers of the blood include leukaemia, lymphoma and myeloma. They can let you know the best time to have the flu vaccine.
If you have had a stem cell transplant, your specialist will usually suggest you wait about 6 months before you have the flu vaccine. Again, the length of time will depend on your individual situation.
Can I get a free flu vaccine?
The flu vaccination is free to people at increased risk of catching flu. This includes people with low immunity due to disease or treatment, such as cancer treatment.
It is also free for many children and those aged 50 years and over.
Speak to your GP if you had cancer treatment some time ago and are unsure if you can have a free vaccine. If you are not eligible, you can book and pay for a vaccine at a range of pharmacies or private healthcare providers.
You can read more about the flu vaccination programme (and who can get a free flu vaccine) where you live:
Wales:
Is the vaccine safe?
Adults
The flu vaccine injection doesn't contain live flu virus, so you won’t develop flu from having it. It is safe to have it while you are having cancer treatment.
But you should check with your doctor if you:
- are allergic to egg (manufacturers make the vaccines from viruses grown in hen’s eggs)
- have had a reaction to a vaccine before
People with an egg allergy can have a flu vaccine with a very low egg content. Or you can have a newer type of flu vaccine grown in cells, not eggs. Ask your doctor about this.
Children
Some pre school and primary school children have the flu vaccine as a nasal spray. Talk to your medical team if your child has cancer. Your doctor may suggest that your child doesn’t have the nasal spray if they have a very weakened immune system. This is because the nasal spray contains a live, but weakened form of the flu vaccine.
Normally, the flu vaccine helps a child to build up their immunity to flu. But if your child has a weakened immune system, the immune system may not be strong enough to build up a response. Without an immune response, the vaccine virus could cause flu. The doctor might suggest your child has the flu vaccine injection instead.
Side effects of the flu vaccine
The vaccine doesn’t usually cause many side effects. But with the injection, you may have:
- slight soreness, swelling or redness around the injection site
- a slight fever or shivering
- aching muscles or joints
- tiredness
- a headache
Possible side effects of the nasal spray include:
- a runny or blocked nose
- a headache
- weakness
- loss of appetite
Contact with other people who have the flu vaccine
Adults
It is safe to be in contact with people who have had the flu vaccine as an injection if you have a severely weakened immune system.
Children
Some pre school and primary school children have the flu vaccine as a nasal spray. Avoid close contact with children who have had the nasal spray if you have a severely weakened immune system. You should do so for 2 weeks following their vaccination.
The nasal spray contains a live but weakened form of the flu vaccine. So there is a very small chance that the vaccine virus could be passed on to you and cause flu if you have a severely weakened immune system.
The injection does not contain a live form, so these precautions do not apply to contact with people who have had the injection.
Ask your healthcare team whether you must avoid contact with children who have had the nasal spray flu vaccine.
