Asthma and Influenza

Influenza, also known as the seasonal flu, is an unpredictable and highly contagious viral infection of the nose, throat and lungs. These viruses travel through air droplets when an infected individual coughs, sneezes or talks. It can spread when someone inhales the air droplets or touches infected objects, transferring germs.

  • The most vulnerable in our society are the most at risk from influenza: children, the elderly and persons with chronic health conditions, like diabetes, cardiac or pulmonary disorders, and asthma.
  • Individuals with chronic health conditions such as asthma have the highest risk for influenza-related complications.
  • Between 500-1,500 Canadians die each year from pneumonia complications related to influenza.
  • Although the burden of influenza can vary from year to year, it is estimated that, in a given year, an average of 12,200 hospitalizations related to influenza and approximately 3,500 deaths attributable to influenza occur.

Effects on Individuals with Asthma

  • Adults and children with asthma are more likely to develop pneumonia after getting sick with influenza than people who do not have asthma.
  • An influenza infection in the lungs can trigger asthma attacks and a worsening of asthma symptoms, which can also lead to pneumonia and other acute respiratory diseases.
  • Asthma is the most common medical condition among children hospitalized with influenza and one of the more common medical conditions among hospitalized adults.
  • If you get sick with influenza symptoms, call your doctor as treatment should begin as soon as possible because antiviral drug treatment works best when started early.

Minimizing Your Risk of Contracting Influenza

Health Canada recommends that the best way to prevent influenza is by getting a flu shot. Dr. Susan Waserman, Chair of Asthma Canada’s Medical and Scientific Committee, especially encourages people with asthma and their families to get a flu shot yearly to help prevent complications with their chronic condition.

 Flu shots are recommended annually to help reduce the frequency of asthma exacerbations, as viral and upper respiratory tract infections can both cause asthma episodes and make people with asthma more sensitive to asthma triggers.”

 It’s also important that anyone who is a caregiver or health worker for vulnerable populations take the flu shot to protect themselves and those they care for. The National Advisory Committee on Inmmunization (NACI) recommends the high dose flu shot for those 65 years of age and older.

Flu Vaccines

Influenza vaccines work by stimulating the body to make antibodies against the influenza virus within about two weeks after vaccination. Antibodies against influenza help provide protection against infection with the viruses that are in the vaccine. Vaccination is important for people with asthma because influenza can cause further inflammation to their airways and lungs. Some influenza vaccine options recommended by the National Advisory Committee on Immunization are listed below.


  • A four-strain influenza vaccine has been introduced as part of Canada’s public health immunization programs.
  • Different than three-strain influenza vaccines (TIV), the four-strain (or quadrivalent) influenza vaccine (QIV) protects against four different influenza virus strains: two influenza A strains and two influenza B strains.
  • The World Health Organization (WHO) recommends that QIV be used where available.

High Dose

  • Older adults can suffer the most severe consequences of influenza.
  • Adults 65 years and older typically experience 70% of hospitalizations and 90% of deaths due to influenza.
  • While most people can recover from influenza in as few as seven days, it generally takes longer for seniors to recover, and they may be at higher risk of developing more severe complications, including pneumonia or worsening underlying medical conditions.
  • NACI has stated that the high-dose influenza vaccine should be used over the standard dose, given the burden of influenza and the good evidence that the high-dose influenza vaccine offers better protection in adults 65 years of age and older.

Getting vaccinated is your best defense against the flu – for you and those around you. For more information about the annual flu vaccination, and whether four-strain of high-dose vaccine is available in your province, speak to your doctor, pharmacist or local public health authority.

The information available on this page is supported by an educational grant provided by Sanofi Pasteur.

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