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Influenza (Flu) Immunization: Myths and Facts

Last Updated: September 16, 2022
HealthLinkBC File Number: 12c
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Influenza vaccines are a safe and effective way to help people stay healthy, prevent illness and even save lives. The influenza virus can cause serious illness and even death.

The influenza vaccines available in B.C. are either inactivated or live attenuated vaccines. The inactivated influenza vaccine is made of killed influenza viruses or parts of the viruses and is given by injection. The live attenuated influenza vaccine is made from weakened influenza viruses and is given as a nasal spray.

Many people use the term flu to refer to any illness caused by a virus, such as the common cold or stomach flu, which can cause confusion. However, the influenza virus causes a respiratory illness that tends to be more severe than these viruses, and is more likely to cause complications.

Myths and facts about influenza and influenza immunization

Myth: Influenza is not a serious illness.

Fact: In years when influenza is widespread in B.C., hundreds of people may die from influenza or its complications, such as pneumonia. Influenza can lead to serious illness in seniors 65 years and older and in other high risk groups.

Myth: I have never had influenza, so I do not need to get an influenza vaccine.

Fact: Symptoms of influenza can vary from mild to severe. Most people can get sick with influenza several times during their lives. An influenza vaccine is the best protection against the influenza virus.

Myth: The influenza vaccines can give me influenza.

Fact: The inactivated influenza vaccine given by injection cannot give you influenza. The vaccine contains killed influenza viruses or parts of the viruses that cannot cause infection.

The live attenuated influenza vaccine given as a nasal spray contains weakened influenza viruses. Common reactions to the live vaccine include mild symptoms such as a runny nose, nasal congestion, cough, sore throat and fever. These symptoms are less severe than those from influenza infection and last a shorter time.

As a precaution, people with weakened immune systems should not get the live vaccine.

Myth: The influenza vaccines cause severe reactions or side effects.

Fact: The influenza vaccines are safe. Most people who get the inactivated influenza vaccine only have redness, soreness or swelling where the vaccine was given. Some people, especially those who get the vaccine for the first time, may have a headache, muscle aches or tiredness. People who receive the live attenuated influenza vaccine may have mild influenza symptoms as described above.

Guillain-Barré Syndrome (GBS) is a rare condition that can result in weakness and paralysis of the body’s muscles. It most commonly occurs after infections. In rare cases, GBS can also occur after some vaccines. GBS may be associated with influenza vaccine in about 1 per million recipients.

Myth: Getting an influenza vaccine every year weakens my immune system.

Fact: Because the influenza virus strains change most years, you need to get immunized each year to be protected against new strains. People who get the vaccine each year are better protected than those who remain unimmunized.

Myth: I should not get an influenza vaccine because I have allergies.

Fact: 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 an influenza vaccine.

Myth: The influenza vaccines protect against the viruses or bacteria that cause colds or stomach illnesses.

Fact: Influenza vaccines do not protect against the viruses or bacteria that cause colds or stomach illnesses, often called the stomach flu. The influenza virus is a respiratory virus and is very different and typically causes more severe illness than the viruses that cause the common cold or the stomach flu. Influenza vaccines only protect against the viruses that cause influenza.

Myth: The vaccines do not work because I still get influenza (the flu).

Fact: There are many different types of viruses that can cause influenza-like symptoms any time of the year, but these are not actually the influenza virus.

The influenza vaccines protect against the strains of influenza viruses that health experts think will likely cause influenza during the current influenza season. The vaccines do not protect against other viruses that cause similar illnesses, such as respiratory syncytial virus (RSV) or parainfluenza. Because the influenza virus strains in the vaccine change most years, you need to get immunized each year to be protected against new strains.

In elderly people and people who have certain chronic health conditions, the vaccines may not prevent influenza completely but may decrease symptoms, complications and the risk of dying from influenza.

Myth: I am pregnant and should not get an influenza vaccine.

Fact: The inactivated influenza vaccine given by injection is considered safe at any stage of pregnancy. People in the second half of pregnancy are at much higher risk of hospitalization due to influenza, especially those in the third trimester. As well, people at any stage of pregnancy who have chronic medical conditions are also at much higher risk of serious influenza complications and should be immunized.

It is not known if the live attenuated influenza vaccine is safe during pregnancy. As a precaution, people who are pregnant, or intending to become pregnant, should receive the inactivated influenza vaccine, which contains killed influenza viruses or parts of the viruses that cannot cause infection.

Myth: I am a nursing mother and should not get an influenza vaccine.

Fact: It is safe for babies to breastfeed after mothers receive the influenza vaccine.

For More Information

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