There are many myths surrounding flu and the flu vaccine. So here are the facts.
The flu vaccine is available on the NHS for adults and children who are considered "at risk", as well as children aged 2 to 10 years old on 31 August 2019.
A bad bout of flu is much worse than a heavy cold.
Flu symptoms come on suddenly and sometimes severely.
They include fever, chills, headaches and aching muscles, as well as a cough and sore throat.
You're likely to spend 2 or 3 days in bed.
If you get complications caused by flu, you could become seriously ill and have to go to hospital.
The injected flu vaccine given to adults contains inactivated flu viruses, so it cannot give you flu.
Your arm may feel a bit sore where you were injected, and some people get a slight temperature and aching muscles for a couple of days afterwards. Other reactions are very rare.
The children's nasal spray flu vaccine contains live but weakened flu viruses that will not give your child flu.
Flu is caused by viruses. Antibiotics only work against bacteria. You may be prescribed antiviral medicines to treat your flu.
Antivirals do not cure flu, but they can make you less infectious to others and reduce the length of time you may be ill.
To be effective, antivirals have to be given within a day or 2 of your symptoms appearing.
A bacterial infection may occur as a result of having the flu, in which case you may be given antibiotics.
The viruses that cause flu can change every year, so you need a vaccination that matches the new viruses each year.
The vaccine usually provides protection for the duration of that year's flu season.
You should have the vaccine no matter what stage of pregnancy you're at.
If you're pregnant, you could get very ill if you get flu, which could also be bad for your baby.
Having the vaccine can also protect your baby against flu after they're born and during the early months of life.
The nasal spray flu vaccine is recommended on the NHS for all healthy 2- and 3-year-olds, plus children in primary school.
In addition, children "at risk" of serious illness if they catch flu are eligible for a flu vaccine on the NHS.
This includes children with a pre-existing illness, such as a respiratory or neurological condition, and children who are having treatment that weakens their immune system, such as chemotherapy.
The flu vaccine is generally given as an injection to children aged 6 months to 2 years and as a nasal spray to children aged 2 to 17 years who have a long-term health condition, except in a few groups in which this is contraindicated and who should receive the injectable vaccine.
The flu vaccine is not suitable for babies under the age of 6 months.
Read more about which children can have the flu vaccine
If you're in 1 of the "at risk" groups, you should still get the vaccine.
As flu is caused by several viruses, the immunity you naturally developed will only protect you against 1 of them.
You could go on to catch another strain, so it's recommended you have the vaccine even if you have recently had flu.
Also, what you thought was flu could have been something else.
You should take up the offer of the flu vaccine when it becomes available, with the best time to have it from the beginning of October to the end of November.
Many people think that taking daily vitamin C supplements will stop them getting flu, but there's no evidence to prove this.