The flu virus is mainly spread by droplets in the air when an infected person coughs, sneezes or talks. People become sick when these droplets enter their noses or mouths, or when they come into contact with objects that have the flu virus on them and touch their noses, mouths or eyes afterwards.

Flu is highly infectious and can spread very quickly – a single individual can infect a large number of people.

While flu is normally spread between humans, other animals (such as pigs, birds and horses) can also harbour the virus which can in turn, infect humans.

Anyone can get flu, however, certain groups of the population are more susceptible than others. These include:

• Children and the elderly

• Pregnant women

• People who suffer from certain conditions such as:

• Chronic respiratory disease (for example, asthma) or breathing difficulties

• Diabetes

• Heart disease

• Kidney disease

• Liver disease

• Neurological or neurodevelopmental conditions (for example, multiple sclerosis)

• Weakened immune system (due to disease or treatment, for example, HIV/AIDS, chemotherapy)

• Spleen problems (for example, sickle cell disease)

Flu symptoms can occur suddenly. People who have flu typically have a fever and experience two or more of the following symptoms:

• Chills

• Fatigue

• Muscle aches in the back, arms or legs

• Headache

• Runny or stuffy nose

• Sore throat

• Shortness of breath or cough

• Loss of appetite

• Diarrhoea and/or vomiting

If you have flu, you may not be able to carry on with your daily routine and may need to stay in bed for a few days.

For a small number of people, particularly those in higher risk groups, flu can cause serious complications. These include:

• Development of serious illness (for example, pneumonia, bronchitis, encephalitis, myocarditis or ear infections)

• Worsening of existing conditions

In severe cases, flu may result in hospitalisation or even death.

A flu infection normally lasts around a week. However, you may feel tired and unwell for several weeks after.

Flu is usually much more severe than a cold. The main symptoms of a cold are a sore throat and stuffy or runny nose; unlike flu, with a cold these symptoms tend to occur gradually (rather than suddenly).

The best way to prevent flu is to get a flu jab each year.

Good health habits can also help prevent the spread of germs which can lead to respiratory illnesses like flu. Some precautions you can take include:

• Covering a cough or sneeze with a tissue

• Cleaning surfaces often to get rid of germs

• Washing your hands regularly

• Avoiding close contact with people who are sick

• Practising good health habits (exercising regularly, eating and sleeping well, managing stress)

Anti-viral medicines are used to treat flu.

It is important to note that because flu is caused by viruses and not bacteria, antibiotics are ineffective against flu.

A flu jab, or vaccination, is the best way to prevent flu. It helps your body produce antibodies that protect it against flu viruses.

The UK Department of Health recommends flu jabs for people who:

• Are aged 65 years or over

• Are more vulnerable to the effects of flu (listed previously)

• Are pregnant

• Live in a residential or nursing home

• Care for an older or disabled person

• Work in the healthcare sector

• Work with poultry

The flu jab is not suitable for certain groups of people. These include those who:

• Have a serious allergy to hens eggs

• Have had a severe reaction to flu jabs in the past

• Are younger than 6 months of age

• Are ill with a fever

If you are unsure about whether you should get a flu jab, consult your healthcare professional.

The flu jab does not contain any live viruses and so it cannot give you flu. Most people who receive the vaccine tolerate it very well.

There are some fairly common side effects. These include:

• Soreness, redness or swelling where the jab was given

• Slight fever

• Muscle aches

Such side effects are often mild and should last no longer than 1–2 days. Any other side effects are rare.

Most people who get a flu jab will not become infected with flu.

However, like any other vaccine, the jab does not give 100% protection against flu. Out of every 100 people who receive the flu jab, 70–80 will not fall ill. The remainder will have some protection, experiencing milder symptoms when they catch the flu.

It is important to note that the flu jab does not protect against:

• The common cold

• Other winter viruses caused by non-influenza viruses

The flu jab normally provides protection for a year.

As flu is more likely to strike in winter, it is best to get a jab in the autumn, before any flu outbreaks occur. Flu jabs are normally available from the beginning of October.

Yes, you should get a flu jab annually, especially if you are at increased risk for flu.

This is because the viruses that cause flu change frequently and the strains that circulate one year are often different from those of the previous year. Every year before the winter flu season, the most likely viruses are identified so that vaccines can be produced to provide protection against the particular strains that will be prevalent in the upcoming flu season.

You can book an appointment to receive your free flu jab (if you fall in the recommended groups – listed above). Vaccinations normally take place in doctors’ surgeries or occupational health departments.