Flu Shots During Pregnancy

How flu vaccine works


About the vaccine

Why get vaccinated against influenza?

Influenza, also called the flu, can cause serious illness and can lead to hospitalization and even death.  Influenza is ranked among the top 10 leading causes of death in Canada. Although the burden of influenza can vary from year to year, it is estimated that each year in Canada, influenza and its complications cause an average of 12,200 hospitalizations and approximately 3500 deaths. 

Getting vaccinated is the best way to protect against influenza. When you get vaccinated, you help protect others as well by reducing the spread of the influenza virus.

How does the influenza vaccine work?

Influenza vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine. 

Influenza vaccines are designed to protect against the influenza viruses that research indicates will be most common during the upcoming influenza season.  "Trivalent" influenza vaccines are made to protect against three different influenza viruses and "quadrivalent" vaccines are made to protect against four different influenza viruses. 

What viruses will the 2017/18 influenza vaccines protect against? 

The 2017/18 influenza vaccines will protect against the following viruses: 

  • A/Michigan/45/2015 (H1N1)pdm09-like virus
  • A/Hong Kong/4801/2014 (H3N2)-like virus
  • B/Brisbane/60/2008-like virus
  • B/Phuket/3073/2013-like virus (in quadrivalent vaccines only)

What types of influenza vaccines are available in BC?

There are several inactivated influenza vaccines and a live attenuated influenza vaccine available in BC.  The inactivated vaccines are made of killed influenza viruses and are given by injection. The live attenuated influenza vaccine is made from weakened influenza viruses and is given as a nasal spray. For more information see:

A note about the live attenuated influenza vaccine: Parents may have heard different reports about the live attenuated influenza vaccine (the nasal spray vaccine).  Canada's National Advisory Committee on Immunization has reviewed the most recent research on the effectiveness of this vaccine and continues to recommend this vaccine as a safe and effective option for children 2 – 17 years of age. Unlike in previous years however, it is no longer preferentially recommended over the inactivated influenza vaccine for children in this age group.

A note about Fluzone High-Dose: Fluzone High-Dose (a high dose trivalent inactivated influenza vaccine) is approved for use in Canada for adults 65 years of age and older. This vaccine is not currently publicly funded in BC; however, it will be available for purchase from pharmacies throughout BC. Canada’s National Advisory Committee on Immunization does not recommend preferential use of this vaccine over the other influenza vaccines available for use in this age group. 

Who should get the influenza vaccine?

Canada's National Advisory Committee on Immunization recommends that everyone 6 months of age and older gets an influenza vaccine, with rare exception.

Who is eligible for a free influenza vaccine?

In BC, influenza vaccines are provided free to people at high risk of serious illness from influenza (such as young children, pregnant women, the elderly and people with certain medical conditions), people able to transmit or spread influenza to those at high risk of serious illness from influenza and people who provide essential community services.

For a list of people eligible for a free inactivated influenza vaccine, see the HealthLinkBC File: Inactivated Influenza (Flu) Vaccine

For a list of people eligible for the free live attenuated influenza vaccine, see the HealthLinkBC File: Live Attenuated Influenza (Flu) Vaccine.

Anyone not eligible for a free influenza vaccine can purchase it at most pharmacies and travel clinics. Some employers also provide free vaccines to employees.

When should I get vaccinated?

Influenza season in Canada generally runs from November through April. In BC, influenza vaccines are usually available in October. Though you can receive this vaccine at any time during the influenza season, for best protection, you should get immunized as soon as possible.

Where can I get the influenza vaccine?

Influenza vaccines are provided at a wide variety of locations across the province including:

  • Public health clinics
  • Pharmacies (*Pharmacists can immunize people 5 years of age and older with the inactivated influenza vaccine, given by injection, and 2 years of age and older with the live attenuated influenza vaccine, given as a nasal spray)
  • Physician’s offices
  • Travel clinics   

To find an influenza vaccine clinic near you, visit the BC Influenza Clinic Locator .  

Why do I need an influenza vaccine every year?

An influenza vaccine is needed every year because protection from the influenza vaccine declines over time. As well, influenza viruses are constantly changing so each year the influenza vaccine is reviewed and updated to protect you against the viruses circulating that year. 

How well does the influenza vaccine work?

The influenza vaccine is the best way to protect against influenza.  How well the vaccine works varies from season to season.  It depends on how well matched the influenza vaccine is with the viruses circulating during the season and on the health status and age of the person being vaccinated.  When the influenza vaccine is well matched with the circulating viruses, it prevents influenza in about 60% to 80% of adults and children receiving the vaccine. Effectiveness is less in the elderly population but studies have demonstrated that the influenza vaccine decreases the incidence of pneumonia, hospital admissions and death in the elderly population.

For more information about the flu vaccine, who should and should not get it, the benefits and possible reactions see the following:

        •       HealthLinkBC File: Inactivated Influenza (Flu) Vaccine
        •       HealthLinkBC File: Live Attenuated Influenza (Flu) Vaccine 
        •       HealthLinkBC File: Why Seniors Should Get Influenza (Flu) Vaccine
        •       HealthLinkBC File: Influenza (Flu) Immunization: Myths and Facts

About the disease

What is influenza (flu)?

Influenza is an infection of the upper airway caused by the influenza virus. It can cause mild to severe illness.  A person with influenza is at risk of other infections, including viral or bacterial pneumonia which is an infection of the lungs.  Serious outcomes of flu infection can result in hospitalization or even death.

Some people, such as seniors 65 years and older, very young children, and people who have lung or heart diseases, certain chronic health conditions, or weakened immune systems are at high risk for serious flu complications. Healthy pregnant women in the second half of their pregnancy are at greater risk of being hospitalized following infection with influenza virus. However, even healthy people can get very sick from the flu and pass it to others.

How influenza spreads

How is influenza spread?

Influenza spreads easily from person to person through coughing, sneezing, or having face-to-face contact. The virus can also spread when a person touches tiny droplets from a cough or sneeze on another person or object and then touches their eyes, mouth or nose before washing their hands.

What are the symptoms of influenza?

Influenza symptoms can include fever, headache, muscle pain, runny nose, sore throat, extreme tiredness, and cough. Children may also experience nausea, vomiting, or diarrhea. Although infections from other viruses may have similar symptoms, those due to the influenza virus tend to be worse.  Symptoms can begin about 1 to 4 days, or an average of 2 days, after a person is first exposed to the influenza virus. Fever and other symptoms can usually last up to 7 to 10 days, but the cough and weakness may last 1 to 2 weeks longer.

For more information about influenza, see the following:

HealthLinkBC File: Facts About Influenza (the Flu)