Seasonal flu is a highly infectious respiratory illness caused by a variety of different flu viruses. It spreads rapidly through droplets dispersed by the coughs and sneezes of infected people.

Each year, a vaccine is developed to protect against the strains of flu virus that are expected to be most prevalent that winter. This 'flu jab' is used not just in the UK, but throughout the Northern hemisphere. It gives good protection (70-80% reliability) against all strains of flu included in the vaccination and lasts for a year.

The entire process of developing the seasonal flu vaccine is led, organised and overseen by the World Health Organization (WHO).

The flu jab is offered to people in at-risk groups. These are people, such as pregnant women and the elderly, who are at greater risk of developing serious complications if they catch flu.

You should check now to see if you or members of your family are in an at-risk group.

This year's flu jab (2011/12)

This winter, the H1N1 strain of the flu virus is one of three strains of flu that the seasonal flu jab protects against. H1N1 is the same strain of flu behind the 2009 swine flu pandemic, and it also caused more than 450 deaths in England last year.

It is important to realise that H1N1 is no different from other strains of flu in regards to the principles of creating a vaccine to protect against it. Its inclusion in this year's seasonal flu jab poses no additional risk. It is included because it is likely to be one of the major flu strains circulating in Britain this winter.

See Seasonal flu jab - about the vaccine for more information about the way that the seasonal flu vaccine is made and tested.

For most people, seasonal flu is unpleasant but not serious and they recover within a week.

However, certain people are at greater risk of developing serious complications of flu, such as bronchitis and pneumonia. These conditions may require hospital treatment. A large number of elderly people die from flu every winter.

The seasonal flu vaccine is offered free of charge to at-risk groups to protect them from catching flu and developing serious complications.

At-risk groups

It is recommended you have a flu jab if you:

• are 65 years of age or over
• are pregnant (see below)
• have a serious medical condition (see box to the right)
• are living in a long-stay residential care home or other long-stay care facility (not including prisons, young offender institutions or university halls of residence)
• are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill
• are a frontline health or social care worker (see below)

Pregnant women

As was the case last year, this winter (2011/12) it is recommended that all pregnant women should have the seasonal flu vaccine irrespective of their stage of pregnancy.

This is because there is good evidence to suggest that pregnant women have an increased risk of developing complications if they get flu, particularly the H1N1 strain.

Studies have also shown that the inactivated flu vaccine can be safely and effectively administered during any trimester of pregnancy. The vaccine itself does not present an increased risk of complications to either the mother or baby.

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

Frontline health or social care workers

Employers are responsible for ensuring that arrangements are in place for their frontline healthcare staff to have the seasonal flu vaccine.

Outbreaks of flu can occur in health and social care settings with staff, patients and residents at risk of being affected.

Therefore, it is very important that frontline health and social care professionals protect themselves by having the flu vaccine and in doing so prevent the spread of flu to colleagues and other members of the community.

If you care for someone who is elderly or disabled, you should also be vaccinated against seasonal flu and you should ensure that the person you are caring for has the flu jab as well.

If you think you need a seasonal flu vaccination (see Who should have it), check with your GP, nurse or local pharmacist.

Most GP surgeries organise special vaccination sessions in the autumn. Go to Find and Choose Services to find details of your local GP surgery or health centre.

The flu virus circulates every winter, usually over a period of a few weeks. The best time to have a flu jab is in the autumn, between late September and early November. Do not wait until the winter, when there is already a flu epidemic.

Glossary

Epidemic

An epidemic is a sudden outbreak of disease that spreads through a population in a short amount of time.

Vaccination

Vaccination or immunisation is usually given by an injection that makes the body's immune system produce antibodies that will fight off a virus.

How the vaccine is made

The seasonal flu vaccine contains different types of flu virus, which are grown in hens' eggs.

They are then inactivated (killed) and purified before being made into the vaccine.

There are currently three types of vaccine that are as effective as each other but made in different ways:

• The first type is made by inactivating whole viruses with organic solvents or detergents ('disrupted live' vaccines).
• The second type is made by extracting and purifying components of the flu viruses ('surface antigen' vaccines).
• The third type uses virosomes, which are the empty envelopes of flu viruses that lack the genetic material of the original virus.

Because the flu virus is continually changing and different types circulate each winter, a new flu vaccine has to be produced each year.

How the flu vaccine composition is decided

The World Health Organization (WHO) decides each February which three flu viruses are likely to be the greatest threat that year.

The decision is made by analysing several thousand flu viruses in the WHO flu laboratories around the world. These laboratories assess which strain has been dominant over the previous winter and look for evidence of new strains that have the potential to spread, and how well the current vaccine protects against them.

Production of the vaccine starts in March each year after the WHO announcement. It is available in the UK from September onwards.

How it protects you

About a week to 10 days after you have had the flu injection, your body starts making antibodies to the virus in the vaccine.

Antibodies are proteins that recognise and fight off germs that have invaded your blood, such as viruses. They help protect you against any similar viruses you then come into contact with.

The flu virus changes every year, so you need to have a flu jab annually to make sure that you are protected against the latest strain of the virus.

Glossary

Antibodies

Antibodies and immunoglobins are proteins in the blood. They are produced by the immune system to fight against bacteria, viruses and disease.

Fever

A high temperature, also known as a fever, is when someone's body temperature goes above the normal 37°C (98.6°F).

Allergic

An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Aches

An ache is a constant dull pain in a part of the body.

Immunisation

Vaccination or immunisation is usually given by an injection that makes the body's immune system produce antibodies that will fight off a virus.

You should not have the seasonal flu vaccine if:

• you have had a previous allergic reaction to a flu vaccine (rare), or
• you have a serious allergy to hens' eggs (very rare), because the vaccine is prepared in hens' eggs.

Generally, if you are healthy, under 65 years of age and do not fall into any of the at-risk groups, it is not necessary for you to have a flu jab as your body can fight off the virus if you become ill with it.

If you are ill with a fever, do not have your flu jab until you have recovered.

If you are pregnant, talk to your GP about having the vaccination. No problems have been reported in pregnant women who have had the flu jab.

Glossary

Allergic

An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

When am I most at risk from flu?

Can I go to work/school if I have been in contact with somebody who has recently been diagnosed with flu?

A person I live with has been diagnosed with flu - do I need to have the flu vaccine?

Does everyone need a flu jab?

Why are certain groups targeted for the flu jab?

Can a GP vaccinate anyone else?

Is my child entitled to the flu vaccine?

How long will the flu jab protect me for?

How long does the seasonal flu vaccine take to become effective?

If I had the flu jab last year, do I need it again now?

Can the flu jab actually cause flu?

When is the best time to get my flu jab?

Is there anyone who cannot receive a flu jab?

Can people get the flu vaccine privately?

Why is it recommended that healthcare workers are vaccinated?

Can I get a flu jab if I'm breastfeeding?

Can you have the seasonal flu vaccine at any time during pregnancy?

I am allergic to penicillin. Can I still have the flu jab?

How do I get the seasonal flu vaccine if my GP has run out?

Do I need Tamiflu and how do I get a prescription?

I have had flu symptoms for five days - can I have visitors?

When am I most at risk from flu?

Influenza reappears every winter, usually over a short period of a few weeks, so that a lot of people get ill around the same time. In a bad year, this can amount to an epidemic, but it is impossible to predict how much flu there will be every year.

Can I go to work/school if I have been in contact with somebody who has recently been diagnosed with flu?

Yes, you should go about your everyday business, but stay at home if you develop flu-like symptoms.

Does everyone need a flu jab?

Ask your GP about having a flu vaccination if you:

• are 65 or over
• are pregnant
• have a serious medical condition (see conditions that put you at higher risk of flu)
• live in a residential or nursing home
• are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill
• are a healthcare or social care professional directly involved in patient care
• work with poultry

For more information, see Who should have it.

Why are certain groups targeted for the flu jab?

Complications such as bronchitis and pneumonia are more common in those with underlying diseases such as those mentioned above, especially if they are also elderly, and related flu deaths are almost entirely in these groups.

In long-stay residential accommodation, influenza vaccination prevents the rapid spread of infection that causes outbreaks.

Can a GP vaccinate anyone else?

The final decision as to who should be offered vaccination is a matter for the patient's medical practitioner, based on the individual's medical history.

Is my child entitled to the flu vaccine?

If your child has flu risk factors, then he/she should have the seasonal flu vaccine. Numbers of recommended doses vary with age, condition and whether the child has had the flu vaccine before.

Children under five without risk factors are not included this year, unlike during the pandemic, when there was evidence that they were at heightened risk. Since many under-fives were either infected during the pandemic or were vaccinated, the expectation was that they would not be at such a high risk this flu season.

How long will the jab protect me for?

The flu jab will protect you for about a year.

How long does the seasonal flu vaccine take to become effective?

About a week to 10 days after you have had the flu injection, your body starts making antibodies to the virus in the vaccine. Antibodies are proteins that recognise and fight off germs that have invaded your blood, such as viruses. They help protect you against any similar viruses you then come into contact with.

If I had the flu jab last year, do I need it again now?

Yes. The viruses that cause flu change every year, which means the flu (and the vaccine) this winter will be different from last winter's.

Can the flu jab actually cause flu?

No. The vaccine does not contain any live virus, so it cannot cause flu. Some people get a slight temperature and aching muscles for a couple of days afterwards and your arm may feel a bit sore where you were injected, but that is all. Any other reactions are rare; flu jabs are very safe.

When is the best time to get my flu jab?

The best time is between late September and early November, ready for the winter. You should not wait until there is a flu epidemic.

Is there anyone who cannot receive a flu jab?

There are very few people who cannot receive an influenza vaccine. The vaccines should not be given to those who have had a confirmed anaphylactic reaction (serious allergic reaction) to a previous dose of the vaccine or any component of the vaccine (including neomycin, kanamycin and gentamicin - antibiotics that may be present in tiny amounts).

The vaccines are prepared in hens' eggs and should not be given to individuals with a known allergic reaction to egg products.

If a person is ill with a fever, the vaccination should be delayed until they have recovered.

Can people get the flu vaccine privately?

If people outside the recommended groups wish to make arrangements to pay for a flu vaccination privately, that is their choice. The flu vaccine may be available from pharmacies such as Boots or Superdrug or in supermarkets such as Tesco and Sainsbury's. It would be provided on the equivalent of a private patient basis and you would have to pay.

Why is it recommended that healthcare workers are vaccinated?

It not only prevents healthcare workers passing on flu to their patients, but should also help the NHS maintain staffing levels during a flu epidemic, when both GPs and other health services are particularly busy.

Can I get a flu jab if I'm breastfeeding?

Yes, there is no evidence of risk from vaccinating pregnant women or those who are breastfeeding.

Can you have the seasonal flu vaccine at any time during pregnancy?

Yes, the seasonal flu vaccine is safe to take whatever the stage of pregnancy, including in the first trimester and around the expected due date.

I am allergic to penicillin. Can I still have the flu jab?

Yes, you can safely have the flu jab if you are allergic to penicillin.

How do I get the seasonal flu vaccine if my GP has run out?

GPs have already been asked to check their stocks. If they have run out, they have been advised to work with neighbouring practices or the primary care trust to obtain further supplies. The vaccine maunfacturers/suppliers still have stocks available for ordering.

Do I need Tamiflu and how do I get a prescription?

Your GP will decide if you need Tamiflu, and will prescribe it if necessary.

I have had flu symptoms for five days - can I have visitors?

You are probably not infectious after five days and will be clear of infectiousness by seven days.

The links below provide information on the flu jab in other languages.

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