Woman with flu virus or influenza

All you need to know about the flu virus

What is ‘The Flu’?

Influenza is an extremely infectious acute respiratory illness caused by the flu virus. Affecting people of all ages, there are flu Outbreaks almost every year and on rare occasions reaching epidemic proportions. These outbreaks usually occur in winter which makes this a seasonal infection.

Is catching the Flu virus serious?

Flu is generally self-limiting with a 2-7 day recovery period for most people. However, for the very young and elderly people who are more vulnerable, flu can be severe and in some cases result in death. Serious respiratory complications can develop, including pneumonia and bronchitis, to which older people and those with certain chronic medical conditions are particularly susceptible. Pregnant women also fall into the risk category of the complications of flu. Hospitalisation may be necessary for some people and recent statistics show that there are between 200 and 500 deaths, mainly in older people. as a result of influenza each winter.

How is the flu virus transmitted?

Flu is extremely infectious. The virus can be spread from person to person by coughing, sneezing. The virus can be transmitted from 1-2 days before development of symptoms and for up to a week following development of the flu.

What are the symptoms of Flu?

Onset of symptoms can be sudden and sever and include:

• Sudden fever,
• Chills,
• Headache,
• Muscle pain
• Sore throat,
• Non-productive dry cough.

How do I know if it is Flu or just a cold?

As symptoms are similar, it can be difficult at times to tell between the common cold and flu. The common cold is not as sever an illness as the flu. Onset of flu symptoms is sudden with fevers and muscle aches. The common cold generally begins gradually with a sore throat and a blocked or runny nose.

Table of Symptoms

The following table provides assistance on distinguishing the difference between seasonal flu and the common cold.


Seasonal flu



High fever lasts 3-4 days





General Aches, Pains

Usual; often severe


Fatigue, Weakness

Can last up to 2-3 weeks

Quite mild

Extreme Exhaustion

Early and prominent


Stuffy Nose






Sore Throat



Chest Discomfort, Cough

Common; can become severe

Mild to moderate; hacking cough

Who are the most at risk?

Anyone can get the flu but anyone suffering from a chronic medical condition, those aged 65 years or over and pregnant women are more at risk of the complications of flu. Chronic medical conditions include chronic heart conditions, chronic respiratory disease, diabetes mellitus and immunosuppression due to disease or treatment.

How can flu be prevented?

Vaccination can prevent the flu. The vaccine is safe and an effective way to help prevent flu infection, avoiding hospitalisation, reducing flu related deaths and illnesses.

What is the seasonal (annual) flu vaccine?

Each year the seasonal (annual) flu vaccine contains three common flu virus strains. The flu virus changes each year this is why a new flu vaccine has to be given each year.

Is the vaccination expensive?

• O’Flynn’s Pharmacy Ardee, offer free vaccines to all over 18 years of age. There is no charge for either the vaccine or administering the vaccine.

Who should be vaccinated?

Vaccination is strongly recommended for:

• Persons aged 65 and over
• Those aged 6 months and older with a long-term health condition such as

– Chronic heart disease (this includes anyone who has a history of having a “heart attack” or unstable angina)
– Chronic liver disease
– Chronic renal failure
– Chronic respiratory disease, including chronic obstructive pulmonary disease (COPD), cystic fibrosis, moderate or severe asthma or bronchopulmonary
– Chronic neurological disease including multiple sclerosis, hereditary and degenerative disorders of the central nervous system
– Diabetes mellitus
– Down syndrome
– Haemoglobinopathies
– Morbid obesity i.e. body mass index over 40
– Immunosuppression due to disease or treatment (these include anyone on treatment for cancer)
• Children aged 6 months and older
– with any condition that can affect lung function especially those attending special schools/day centres with cerebral palsy or intellectual disability
– on long-term aspirin therapy (because of the risk of Reyes syndrome)
• Pregnant women (vaccine can be given at any stage of pregnancy)
• Healthcare workers
• Residents of nursing homes and other long stay institutions
• Carers (the main carers of those in the at risk groups)
• People with regular contact with pigs, poultry or water fowl.

How does the vaccine work?

When a vaccine is administered, antibodies to the virus are produced in the person’s system. These antibodies will attack the virus when the vaccinated person comes into contact with someone who has the flu, effectively fighting off the virus.
How effective is seasonal flu vaccine?
This year’s flu vaccine is expected to be up to 90% effective.

How long is the flu season?

The flu season lasts from October to the end of April In the Northern hemisphere. It is recommended that all those in the risk group, i.e. 65+ years of age, young children and pregnant women can be vaccinated up until the end of April.

Is the flu virus vaccine safe?

Yes. For over 60 years, millions have been vaccinated worldwide. Any reactions are usually mild with severe side effects being very rare.

Is thiomersal used in the flu vaccine?

Some people are concerned about the use of thiomersal, a mercury-containing compound used to prevent bacterial and fungal growth in some vaccines during storage. However, thiomersal is not used in the flue vaccine. No. There is no thiomersal in the vaccine used in the 2015/2016 flu campaign.

Will I get the flu following the flu vaccine?

No, the flu vaccine contains dead or inactive viruses and cannot cause flue. However, be aware that it takes 10 – 14 days for the vaccine to start protecting against flu.

When is the optimum time to be vaccinated?

The end of September/October is the best time to be vaccinated annually.

Will there be side effects from the vaccination?

Commonly side effects will be mild and may include soreness, redness or swelling at the injection site. Some may experience light Headache, fever, aches or tiredness. Some people may experience mild sweating and shivering as their immune system responds to the vaccine but this is not flu and will pass in a day or so.

When will the vaccine start working?

10-14 days is the expected time for the vaccine to begin protecting against flu.

Who should NOT get the flu vaccine?

The vaccine should not be given to those with a history of severe allergic (anaphylaxis) reaction to a previous dose of the vaccine or any of its constituents.

Can people with egg allergy receive the flu vaccine?

Those with confirmed egg anaphylaxis and non-anaphylactic egg allergy can be given an influenza vaccine with an ovalbumin content <0.1μg per dose. Inactivated Influenza vaccine (Split Virion) BP (Sanofi Pasteur) contains less than 0.1μg ovalbumin per dose and so can be administered in accordance with the Table below.



Non-anaphylactic egg allergy without severe asthma

Seasonal influenza vaccine with ovalbumin content

<0.1μg per dose, in primary care, with observation for 60 minutes.

Egg anaphylaxis or egg allergy and severe asthma

Refer to hospital specialist for vaccination with seasonal influenza vaccine with ovalbumin content <0.1μg per dose.

Skin testing is NOT necessary and vaccines should be given as a single dose with observation for 60 minutes.

When should vaccination be postponed?
There are very few reasons why vaccination should be postponed. Vaccination should be re-scheduled if you have an acute illness with a temperature greater than 38°C.

Where do I get vaccinated?

• People aged 18 years or older may attend either their GP or Pharmacist – O’Flynn’s Pharmacy offer the vaccine and administration completely free.
• People under 18 years of age should attend their GP for vaccination.

Things to remember

For those 65+ or those who have a long term medical condition, it is advisable to consult your medical advisor about the pneumococcal vaccine which protects against pneumonia, if you have not previously received it.
A once only booster vaccination is recommended 5 years after the first vaccination for those;
• Aged 65 years and older if they received vaccine more than 5 years before and were less than 65 years of age at the time of the first dose,
• Less than 65 years of age and whose antibody levels are likely to decline rapidly e.g. asplenia, hyposplenism, immunosuppression, chronic renal
&nbsp:&nbsp: disease or renal transplant.

Finally, look after yourself this winter.

1. Eat healthily and try to make one of your daily meals a hot one.
2. Keep yourself warm: wear several layers when outside and keep at least one room heated during the day.
3. Keep as active as you possibly can.
4. Go to your pharmacy or doctor and get your flu vaccination.