Flu (influenza) is a highly infectious illness that spreads rapidly through the coughs and sneezes of people who are carrying the virus.

Flu symptoms can hit quite suddenly and severely. They usually include fever, chills, headaches and aching muscles. You can often get a cough and sore throat.

Because flu is caused by a virus and not bacteria, antibiotics won't treat it.

Anyone can get flu, but it can be more serious for:

• people aged 65 or over
• people of any age (including children over six months old) with a serious medical condition

If you are in one of these two groups, you're more vulnerable to the effects of flu (even if you're fit and healthy) and could develop more serious illnesses, such as bronchitis and pneumonia, which could result in hospitalisation.

Flu can also make existing medical condition worse.

Get the jab

The best time of the year to get a flu vaccination (jab) is in the autumn. It's free and it's effective against the latest flu virus strains.

Even if you've already had a flu jab in previous years, you need another one this year. The flu jab may only protect you for a year. This is because the viruses that cause flu are always changing. 

The H1N1 virus that caused the swine flu pandemic last year will still be around this winter, so this year's (2010-2011) seasonal flu vaccination will include a vaccine to protect against this virus.

See your GP about the flu jab if you're 65 or over, or if you have any of the following problems (however old you are):

• a serious heart or chest complaint, including asthma
• serious kidney disease
• diabetes
• lowered immunity due to disease or treatment such as steroid medication or cancer treatment
• if you have ever had a stroke

Your GP may advise you to have a flu jab if you have serious liver disease, multiple sclerosis (MS) or some other diseases of the nervous system.

If you think you may need a flu vaccination, check with your GP, practice nurse or your local pharmacist. If a nurse visits you regularly, ask about getting your flu vaccination. Most GP surgeries arrange vaccination sessions in the autumn.

Pregnant women

This winter (2010-11), the seasonal flu vaccine is being offered to all pregnant women who haven't already had the swine flu vaccine. This is because the swine flu (H1N1) virus will still be circulating this winter and pregnant women who catch this strain are at an increased risk of severe disease and flu-related hospital admissions.

However, if you are pregnant and have already had the swine flu vaccination you do not need the seasonal flu vaccination. If you are pregnant and in any of the clinical risk groups, you should still have your seasonal flu vaccination.

Talk to your GP or midwife if you're unsure about what vaccination you should have.

The pneumo jab

When you see your GP for a seasonal flu jab, ask whether you also need the 'pneumo jab' to protect you against some forms of pneumococcal infection. It's available to everyone aged 65 or over, and for younger people with some serious medical conditions.

Kids and carers

If you're the parent of a child (over the age of six months) with a long-term condition, speak to your GP about the flu jab. Your child's condition may get worse if they catch flu.

If you're the carer of an elderly or disabled person, make sure they've had their flu jab. As a carer, you could be eligible for a flu jab too. Ask your GP for advice or go to Carers Direct for information about Flu jabs for carers.

How effective is it?

No vaccine is 100% effective, however,  people who have had the flu jab are less likely to get flu. If you do get flu despite having the jab, it will probably be milder than if you haven't been vaccinated.

The flu jab doesn't cause flu as it doesn't contain live viruses. However, you may experience side effects after having the jab, such as a temperature and aching muscles for a couple of days afterwards. Your arm may feel sore at the site where you were injected. More severe reactions are rare.

The flu vaccine only protects against flu, not from other viruses, such as the common cold.

Who shouldn't have it?

You should not be given the flu vaccination if you have a serious allergy to hens' eggs or if you have had a serious reaction to a flu vaccination before.

Not all the seasonal flu vaccines available this year are suitable for children under five years of age. Please make sure that you discuss this with your GP beforehand.

Speak to your GP, practice nurse or pharmacist if you have any further questions.

Read more about the seasonal flu jab.