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Flu Vaccine

Flu spreads easily. Getting vaccinated every year is the best way to protect yourself from the flu and its 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. Consult the details of the Flu Vaccination Program to know how to proceed and where to get vaccinated.

Description of Vaccine

In Quebec, the vaccine is available in 2 forms:

The vaccine offered in Canada contains virus strains expected to circulate the most during the fall and winter in the northern hemisphere. The flu virus strains included in the vaccines are determined each year by the World Health Organisation (WHO) for the northern and southern hemispheres.

Injectable Vaccine

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

For the 2014-2015 season, the injectable vaccine offered under the Quebec Flu Vaccination Program contains the following 3 strains:

  • A/California/7/2009 (H1N1)
  • A/Texas/50/2012 (H3N2)
  • B/Massachusetts/2/2012

An injectable vaccine made from 4 different strains is also available on the market but is not offered under the Flu Vaccination Program.

People aged 6 months and over can receive the injectable vaccine, unless otherwise contraindicated. However, children aged 2 to 17 should receive the intranasal vaccine.

Only certain people can receive the injectable vaccine for free under the public Flu Vaccination Program. To find out more, see the list of people eligible to receive the injectable vaccine for free.

Intranasal Vaccine

Intranasal vaccine is introduced into the body through a spray in the nose, a jet into each nostril. In most cases, this type of vaccine can be administered even in the presence of nasal discharge.

For the 2014-2015 season, the injectable vaccine offered under the Quebec Flu Vaccination Program contains the following 4 strains:

  • A/California/7/2009 (H1N1)
  • A/Texas/50/2012 (H3N2)
  • B/Massachusetts/2/2012
  • B/Brisbane/60/2008

People aged 2 to 59 may receive intranasal vaccines, unless otherwise contraindicated. Intranasal vaccine is recommended only for children aged 2 to 17 years old, while the injectable vaccine is recommended for all other people.

Studies show that intranasal vaccine is most effective in children aged 2 to 17 years old. Also, it protects much longer than injectable vaccine. Intranasal vaccine is therefore recommended and given for free to certain children between 2 and 17 years old under the Flu Vaccination Program. To learn more, see the list of people eligible to receive the intranasal vaccine for free.

Vaccine Safety

Flu vaccine is safe. It cannot transmit flu or other illnesses. In fact, the viruses or a part of the viruses that it contains are killed or too weak to reproduce and cause the flu.

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 Quebec 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 flu vaccine generally takes 2 weeks before being fully effective.

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

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. To learn more, go to the Differences between Flu and Cold page.

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

The vaccine therefore does not offer 100% protection against the flu. The vaccine prevents the flu in about 60% of healthy people when the strains of viruses it contains correspond to strains circulating.

For people aged 60 and over and those with chronic illnesses, the vaccine especially help reduce the risks of complications from the flu, hospitalisation and death.

Vaccinating Children

It is important to vaccinate children so that they may be protected against the flu and its complications. If your child does not feel well the day of the vaccination, see the Conditions for Postponing Vaccination section to know if you must delay their vaccine.

Here is some information on vaccinating children according to their age:

Children Less than 6 Months Old

It is not recommended to vaccinate children aged less than 6 months. Indeed, the effectiveness of the vaccine has yet to be proven for children that age. The vaccine is therefore not offered to them.

However, children less than 6 months may also catch the flu. In addition, they are part of the people most at risk for presenting complications. It is therefore important that all people around children less than 6 years old be vaccinated to avoid transmitting the flu to them.

If you have a child that is less than 6 months old, you and the people around you can receive the vaccine for free under the Flu Vaccination Program.

Children Less than 9 Years Old

Children less than 9 years old getting the flu vaccine for the first time must receive 2 doses of vaccine. The second dose must be given a month after the first. Parents must therefore plan 2 appointments to get their child a flu vaccination.  

Indeed, as most vaccines given in childhood, the first injection of the flu vaccine must be followed by a booster dose. The first dose of the vaccine allows the child’s immune system to, in a way, ‘get acquainted with the virus’ and to fight it, but for only a few weeks. The second dose allows the child’s immune system to produce more antibodies to fight the virus on a longer term.

It is therefore very important that children less than 9 years old getting the flu vaccine for the first time receive the two doses of vaccine. The second dose will allow them to be best protected during the entire flu season.

This procedure also applies to children who received the vaccine against pandemic (H1N1) 2009 flu virus. These children should receive 2 doses of the vaccine if they are getting a flu vaccine for the first time.

Only children less than 9 years old who have already received the flu vaccine need to receive a single dose of it.

People Aged 9 and Up

From the age of 9, children that get the flu vaccine receive a single dose of it, even if they have never received a flu vaccine before.

The immune system of a 9 year old child is indeed sufficiently developed to produce enough antibodies to protect them with a single dose of the vaccine.

Conditions for Postponing Vaccination

There are very few reasons for delaying getting a vaccine.

As such, people with a cold can get vaccinated with no problem. If a person to receive an intranasal vaccine has too much nasal discharge, it is possible for them to get an injectable vaccine.

Only a serious illness can cause a vaccinator to delay a vaccine after evaluating the general condition of the person to be vaccinated. The fact of having a fever is not the only indication of a serious illness.

Side Effects

Some reactions may occur following vaccination.

The Nature and Frequency of Possible Reactions to Injectable Vaccine  

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)

  • Redness, swelling at site of injection
  • Muscle pain
  • Headache
  • Fatigue
  • Loss of appetite
  • Drowsiness (difficulty staying awake)
  • Irritability

(Less than 10% of people)

  • Bruising or itching at the injection site
  • Fever, chills, joint pains and discomfort, particularly in people receiving the flu vaccine for the first time
  • Nausea
  • Vomiting
  • Diarrhea
  • Stomach ache
  • Red eyes, sore throat, coughing and difficulty breathing (known as oculorespiratory syndrome or ORS)

(Less than 1% of people)

  • Swelling of the face (part of ORS reaction)
  • Skin rash
  • Dizziness
  • Swollen glands


(Less than 1 person in 1000)

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

The Nature and Frequency of Known Reactions to Intranasal Vaccine

Frequency Known Reactions to Intranasal Vaccine

(Less than 10% of people)

  • Runny nose or nasal congestion
  • Headache
  • Fatigue or discomfort

(Less than 1 person in 1000)

  • Allergic reaction

What to do After Vaccination

Tips to follow immediately following vaccination

Wait 15 minutes before leaving premises where vaccine is received.

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

Tips to follow at home

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

In case of pain or fever, take an acetaminophen such as Tylenol® or an 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

Extremely Rare Reactions

Extremely rare reactions may occur after a flu vaccine.

The Guillain-Barré syndrome (GBS) is one such reaction. 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 most cases, GBS occurs following infection of the intestines or lungs. It mostly affects young adults and people aged 60 years and older.

The risk of having Guillain-Barré syndrome after receiving a flu vaccine, if such risk exists, 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.

Last update: October 9, 2014 8:44 AM

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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