Common Questions about Influenza (Flu)

Find answers to common questions about Influenza (Flu). Learn how it spreads, how long after exposure symptoms take to appear and what symptoms to look for. Find out what you can do to prevent influenza, including vaccination and handwashing. You can also find more resources about influenza in our Influenza (Flu) Season health feature.

Visit ImmunizeBC: Frequently asked questions about influenza vaccines for more evidence-based immunization information and to find answers to your immunization questions.

General Information on Influenza

1. What causes Influenza?
Influenza or “flu” is an infection of the upper airway, caused by an influenza virus.
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2. 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, symptoms caused by the influenza virus tend to be worse.
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3. How is Influenza spread?

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

An infected person can spread the influenza virus even before feeling sick. An adult can spread the virus from about 1 day before to 5 days after symptoms start. Young children may be able to spread the virus for a longer period of time.
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4. How long does it take to show signs of influenza after being exposed?
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 last up to 7 to 10 days, but the cough and weakness may last 1 to 2 weeks longer.
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5. What is the home treatment for Influenza?
If you get sick with influenza, home treatment can help ease symptoms. Follow the self-care advice below:
  • Get plenty of rest
  • Drink extra fluids to replace those lost from fever
  • Avoid smoking and ask others not to smoke in the house
  • Breathe moist air from a hot shower or from a sink filled with hot water to help clear a stuffy nose

Anti-influenza drugs or antivirals are available by prescription. For them to work best, you must take them within 48 hours after your symptoms start . If you take them within 12 hours, they will shorten symptoms by about 3 days. If you take them within 2 days from the start of your symptoms, your symptoms will be shortened by about 1.5 days. Non-prescription cough and cold medications are available for relief of influenza symptoms.

Non-prescription cough and cold medications are available for relief of influenza symptoms. These medications are not recommended for children under 6 years old

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6. How do you prevent Influenza?
You can reduce the risk of getting influenza or spreading it to others by:
  • Washing your hands regularly
  • Cleaning and disinfecting objects and surfaces that many people touch
  • Promptly disposing of used tissues in the waste basket or garbage
  • Coughing and sneezing into your shirt sleeve rather than your hands
  • Staying home when you are ill
  • Getting an influenza vaccine
Getting an influenza vaccine can help prevent you from getting sick with influenza and from spreading it to others.
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7. What are some risks or complications of Influenza?

Influenza can cause serious illness and can lead to hospitalization and even death. A person with influenza is at risk of other infections, including viral or bacterial pneumonia, which is an infection of the lungs.

Young children and the elderly are especially vulnerable and at high risk of serious illness from influenza. If you are pregnant or if you have certain medical conditions, you are also at higher risk.

For people with chronic diseases, influenza can lead to pneumonia, respiratory failure and other complications.

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8. When should I see a health care provider?

Consult your health care provider early if you develop flu-like symptoms and you have a condition that puts you at higher risk of complications.

Call your health care provider if you develop symptoms of bacterial infection such as new or worse cough with:

  • Ear pain
  • Nasal drainage that changes from clear to colored after 7-10 days
  • Persistent fever
  • Productive cough
  • Sinus pain
  • Sore throat
  • Yellow, green rust-colored or bloody mucus

You should also call your health care provider if your symptoms get worse, including shortness of breath or difficulty breathing, chest pain, or signs of dehydration ( dizziness when standing or low urine output).

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Vaccine Recommendations

1. How do Influenza vaccines work?

The influenza vaccines work by creating antibodies in the body about two weeks after you get the vaccine. These antibodies provide protection against infection with the viruses that are in the vaccine.

An influenza vaccine is needed every year as influenza viruses are constantly changing. Each year the viruses used to make the vaccine also change. This helps protect you against the viruses circulating that year. Protection from the influenza vaccine declines over time.

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2. What is in the flu vaccine?

The 2021-22 seasonal quadrivalent vaccines contain

  • A/Victoria/2570/2019 (H1N1)pdm09-like virus;
  • A/Cambodia/e0826360/2020 (H3N2)-like virus;
  • B/Washington/02/2019-like virus; and
  • B/Phuket/3073/2013-like virus

The A/Victoria and A/Cambodia strains were not contained in the 2021/22 season vaccine.

There are several inactivated influenza vaccines available in B.C. The inactivated vaccines are made of killed influenza viruses and are given by injection.

Live Attenuated Influenza Vaccine (the nasal spray vaccine): Live attenuated influenza vaccine (also known as LAIV or Flumist®) is made of live weakened viruses and is given as a nasal spray. It is intended for those eligible individuals 2-17 years of age (inclusive).

Publicly-funded influenza vaccines available in B.C. for 2021/22 include:

  • Quadrivalent Inactivated Influenza Vaccines (QIIV)
    • Alfuria®  Tetra (Seqirus Canada Inc.)
    • FluLaval® Tetra (GlaxoSmithKline)
    • Fluzone® Quadrivalent (Sanofi Pasteur Limited)
    • Fluzone®  High-Dose Quadrivalent (Sanofi Pasteur Limited)
  • Quadrivalent Live Attenuated Influenza Vaccine (LAIV-Q)
    • Flumist® Quadrivalent (AstraZeneca Canada)

To learn more about this year’s seasonal influenza vaccine, visit ImmunizeBC: Influenza and BCCDC: Intended Use of Influenza Vaccines.


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2. Who should get the Influenza vaccine?

Canada’s National Advisory Committee on Immunization (NACI) recommends that everyone 6 months of age and older gets an influenza vaccine. People at higher risk of serious illness from influenza include children 6 months to less than 5 years of age and seniors 65 years and older. You are also at higher risk if you are pregnant or have certain medical conditions.

In B.C., the inactivated influenza vaccine or “flu shot” is free this year for the following groups:

  • People at high risk of serious illness from influenza
  • People who can transmit or spread influenza to others who are at high risk of serious illness from influenza.
  • Essential workers such as police officers, firefighters, and ambulance attendants
  • Farmers and those who work with live poultry

To learn more about who is eligible for a free influenza vaccine see HealthLinkBC File # 12d Inactivated Influenza (Flu) Vaccine.

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3. Who should not receive the Influenza vaccine?

Speak with your health care provider if you:

  • Had a life-threatening reaction to a previous dose of influenza vaccine, or any part of the vaccine (people with egg allergies can be safely immunized)
  • Had severe oculo-respiratory syndrome after a previous flu shot
  • Developed Guillain-Barré Syndrome (GBS) within 8 weeks of getting any influenza vaccine without another cause being identified
  • Are receiving a checkpoint inhibitor to treat cancer. This may affect when you should get the vaccine
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4. Should my child under 6 months old get the vaccine?
Children less than 6 months of age should not get the vaccine because it is not known to be effective at this age.
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5. I’m not feeling well. Should I get the vaccine?
There is no need to delay getting immunized because of a cold or other mild illness. However, if you have concerns speak with your health care provider.
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6. What is the Influenza Prevention Policy?

B.C. has an Influenza Prevention Policy to protect high risk people from getting influenza. Those at high risk include children, pregnant women, seniors, and people with certain medical conditions.

Health care workers are required to be immunized against influenza or wear a mask when they are in patient care areas during the influenza season. Students, volunteers and visitors to health care facilities and other patient care locations are also expected to wear a mask if they did not get an influenza vaccine.

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At Risk Populations (children, pregnant women, seniors, certain medical conditions)

1. Can I get the Influenza vaccine while I’m pregnant?
The inactivated influenza vaccine or flu shot is considered safe at any stage of pregnancy. If you are in the second half of pregnancy, you are at higher risk of hospitalization due to influenza, especially during the third trimester. If you are pregnant and have a chronic medical condition, you are at higher risk of serious influenza complications and should be immunized. If you are pregnant or intending to become pregnant, you should receive the inactivated influenza vaccine or flu shot, which contains killed influenza viruses that cannot cause infection.
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2. Can I get the Influenza vaccine while breastfeeding?
It is safe for babies to breastfeed after mothers receive the influenza vaccine.
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3. Can my 3-month-old be vaccinated?
Children less than 6 months of age should not get the vaccine because it is not known to be effective at this age.
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4. Should seniors get the influenza vaccine?
As people age, they may be at higher risk of complications from influenza. For this reason, seniors aged 65 years and older are advised to get an inactivated influenza vaccine or flu shot each year.
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5. Should individuals with neurologic or neurodevelopment conditions get the influenza vaccine?
Children and adults with neurologic and neurodevelopmental conditions are recommended to get the influenza immunization .
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Vaccine Safety

1. Is the influenza vaccine safe?
The influenza vaccines are safe. You may have redness, soreness or swelling where the vaccine was given. Some people, especially those who get the flu shot for the first time, have a headache, muscle aches or tiredness.
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2. Is it safe to get the influenza vaccine if I’m pregnant?
The inactivated influenza vaccine or flu shot is considered safe at any stage of pregnancy. During the second half of pregnancy, you are at higher risk of hospitalization due to influenza, especially during the third trimester. As well, during any stage of pregnancy those who have chronic medical conditions are also at higher risk of serious influenza complications and should be immunized.
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3. Is it safe to get the influenza vaccine if I’m breastfeeding?
It is safe for babies to breastfeed after mothers receive the influenza vaccine.
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4. Can I or my child get the vaccine if either one of us has a cold?
There is no need to delay getting immunized because of a cold or other mild illness. However, if you have concerns speak with your health care provider.
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5. I am allergic to egg, is it ok to get the vaccine?
Most people with allergies can get an influenza vaccine without any problems. However, if you have had a severe allergic reaction to a previous dose of influenza vaccine or any part of the vaccine, talk to your health care provider. You may need to be tested for allergies before being immunized. People with egg allergies can be safely immunized with the inactivated influenza vaccine.
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Other Questions on Influenza and Influenza Vaccinations

1. Where can I get the Influenza vaccine?

You can get the influenza vaccine at public health units, community health centers, primary care homes, doctor’s offices, travel health clinics and pharmacies (for those 5 years and older). Visit ImmunizeBC to find a health unit near you.

For more HealthLink BC File topics, visit www.HealthLinkBC.ca/healthfiles. Your local public health may have printed copies that they can give you.

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2. Is the influenza vaccine free?

In B.C., the influenza vaccine is free to people who are at high risk of serious illness from influenza (such as young children and the elderly or those who are pregnant or have certain medical conditions), those able to spread influenza to those at high risk and people who provide essential community services.

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3. Once vaccinated with the influenza vaccine how long does it take for the vaccine to be effective?
It takes about 2 weeks for the vaccine to be effective.
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Useful Links

HealthLinkBC

BCCDC

ImmunizeBC

Government of Canada

Last updated: September 2021

Is it an emergency?

If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be a life-threatening emergency. Call 9-1-1 or the local emergency number immediately.
If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.

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