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Flu Vaccine

Flu spreads easily. Getting vaccinated is the best way of protecting yourself against flu and resulting complications.

The vaccine allows the body to produce antibodies to fight the flu. However, studies show that the number of antibodies can decrease about 6 months after vaccination. This reduction particularly affects young children, seniors and people with a weakened immune system.

In addition, viruses that cause flu constantly change. The composition of flu vaccines are reviewed annually in order to include the virus strains most likely to be in circulation during the flu season.

For these reasons, it is highly recommended you get vaccinated each year in order to protect yourself from flu complications. Check out all the details on the seasonal flu vaccination program to know how and where to get vaccinated.

Description of Vaccine

Each year, the World Health Organization (WHO) determines the three strains of flu viruses most likely to circulate during the fall and winter in the northern and southern hemispheres. Vaccines offered in Canada contain strains likely to circulate in the northern hemisphere.

As such, each year in the fall, a vaccine containing strains of the virus designated by WHO is given in Québec.

The vaccine produced for the 2013-2014 contains the following three strains:

  • A/California/7/2009 (H1N1)
  • A/Victoria/361/2011 (H3N2)
  • B/Massachusetts/2/2012

Types of Vaccine

In Québec, the vaccine is offered in two forms:

Injectable Vaccine

The injectable vaccine is administered into the body through an injection done with a syringe.

People aged 6 months and over can receive the injectable vaccine, unless otherwise contraindicated.  

Composition of Injectable Vaccine

Injectable vaccine contains no living virus. It is produced from parts of weakened viruses. It also contains a small quantity of thimerosal as preservative, traces of sucrose, deoxycholate sodium or Triton X-100 (products used to separate viruses to be included in the vaccine), sodium chloride, potassium chloride, sodium phosphate dibasic heptahydrate, potassium phosphate monobasic and water. In addition, the vaccine contains traces of egg protein and formaldehyde. Some vaccines may also contain minute amounts of neomycin and saccharose.

Intranasal Vaccine

Intranasal vaccine is introduced into the body through a spray in the nose, a jet into each nostril. In the majority of cases, this type of vaccine can be given even if the nose is congested.

People aged between 2 and 59 may receive intranasal vaccines, unless otherwise contraindicated.

However, only certain people can receive intranasal vaccine in the public health system.

People Who Can Receive Intranasal Vaccine in the Public Health System

In the public health system, intranasal vaccine is only given to children between 2 and 17 years of age:

  • Who are at high risk of complications
  • Who live with people at high risk of complications

In fact, studies show that intranasal vaccine is more effective among these children. Also, it protects much longer than injectable vaccine.

Hence the reason intranasal vaccine is recommended for them, and offered free of charge as part of the Flu Vaccination Program.

Composition of Intranasal Vaccine

Intranasal vaccine is produced from weakened live viruses. It also contains a little amount of porcine gelatin hydrolysate type A, saccharose, arginine hydrochloride, monosodium glutamate, di-potassium monohydrogen phosphate, potassium dihydrogen phosphate and gentamicin in tiny quantities. The vaccine also contains traces of egg proteins.

Vaccine Safety

Flu vaccine is safe. It cannot transmit flu or other illnesses. Viruses or parts of the virus it contains are too weakened to reproduce and cause flu.

You must also be aware that the vaccine protects only against strains of the flu virus that it contains. It does not protect against other respiratory infections such as the cold. Flu is often confused with cold. For more on this, see Differences between Flu and Cold.

In Canada and at the World Health Organization (WHO), there are several vaccination surveillance programs. These programs ensure, among other things, the quality of vaccines offered. Among these is the Québec surveillance program, ‘Effets secondaires possiblement reliés à l’immunisation’ (ESPRI). This program was established in 1990 by the Ministère de la Santé et des Services sociaux.

Effectiveness of Vaccine

The vaccine takes two weeks before being fully effective.

The protection offered by the vaccine may vary from person to person, but it lasts at least 6 months.

Factors that Determine Effectiveness

The vaccine’s effectiveness depends on the following:

  • The age of the person vaccinated
  • The state of the person’s immune system, meaning the system that allows their body to defend itself against infections
  • The degree of kinship between the virus strains circulating and those contained in the vaccine

As such, vaccine against flu does not offer 100% protection. When the strains of virus it contains correspond to the strains circulating, the vaccine prevents flu in about 70 to 90% of people in good health.

In people aged 60 and over, or people with a chronic disease, the vaccine works mostly to lower the risk of complications, hospitalization and death.

Vaccine Not Recommended for Children Less Than 6 Months of Age

It is not recommended to vaccinate children less than 6 months old as the effectiveness of the vaccine has yet to be proven for children this age. However, they may also catch flu.

If you have a child that is less than 6 months old, it is important that everyone in their entourage is vaccinated to avoid transmitting them flu. You may receive the vaccine for free as part of the Flu Vaccination Program.

Doses Required For First Vaccination

Children Less Than 9 Years Old

In order to be well-protected, children less than 9 years old who are getting vaccinated for the first time against flu must receive 2 doses of vaccine. These doses must be administered with a one month interval between them.

People Aged 9 and Up

People 9 years old and up who are receiving the vaccine against flu for the first time get a single dose.

Side Effects

The vaccination may cause certain reactions.

The Nature and Frequency of Possible Reactions  

Frequency Possible Reaction to Vaccine

In most cases
(More than 50% of people)

  • Pain at the injection site

Very often
(Less than 50% of people)

  • Pain and swelling at the injection site
  • Muscle soreness
  • Headache
  • Fatigue

(Less than 10% of people)

  • Bruising or itching at the injection site
  • Fever, shivering, joint pain and discomfort, particularly in people vaccinated for the first time against flu
  • Red eyes, sore throat, coughing, and difficulty breathing (this is referred to as Ocular respiratory syndrome (ORS))
  • Runny nose or nasal congestion (caused by intranasal vaccine only)

(Less than 1% of people)

  • Facial swelling; this reaction is part of ORS
  • Skin rash
  • Nausea, dizziness


(Less than 1 person in 1000)

  • Convulsions (body stiffens and muscles contract in a  jerky and involuntary manner)
  • Numbness
  • Nevralgia (pain along the path of a nerve)

What to Do

In the Minutes after Receiving Vaccine

Stay for 15 minutes in the waiting room of the place you have just received the vaccine.

If you feel side effects, immediately inform the person giving the vaccine. The person giving the vaccine will be able to treat you immediately.

At Home

If you experience redness, pain or swelling at the injection site, apply a cold, damp compress at the injection site.

In case of pain or fever, use acetaminophen like Tylenol® for example, or ibuprofen such as Advil®.

When to Seek Medical Help

See a doctor if one of the following applies to you:

  • You experience serious and unusual symptoms
  • Your symptoms get worse instead of improving
  • Your symptoms last over 48 hours

Unusual Reactions

Unusual reactions may occur after flu vaccination. However, such reactions are extremely rare.

Among such reactions, is the Guillain-Barré Syndrome, also called GBS. This syndrome causes progressive paralysis, meaning that one or more parts of the body go numb until you are no longer able to move. This paralysis eventually disappears, but it can sometimes leave permanent effects. The cause of GBS is unknown. In the majority of cases, GBS occurs following infection of the intestines or lungs, especially among young adults and people aged 60 years old or more.

The risk of having Guillain-Barré Syndrome after receiving flu vaccine is extremely low. In fact, there is less of a chance of developing GBS after flu vaccination than after contracting an infection such as the flu.

Serious allergic reactions are also extremely rare. If ever they occur, it is in the few minutes after the vaccination.

Notice to People that Have Experienced Side Effects

If you have already experienced major side effects after receiving flu vaccine, consult your doctor or a nurse before getting vaccinated. They can evaluate the risks and advantages of the vaccination depending on your age and health status.

Last update: October 24, 2013 2:30 PM

The information on this website by no means replaces the advice of a health professional. If you have questions regarding your health, contact Info-Santé 8-1-1 or see a health professional.

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