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
  • In fact, 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 the Medical and Scientific Committee of Asthma Canada, 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 should 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 include:


  • 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.
  • The high-dose influenza vaccine has been demonstrated in a large, randomized controlled trial to be more than 24% more effective than a standard-dose vaccine in adults 65 years of age and older against the flu.

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 ose vaccine is available in your province, speak to your doctor, pharmacist or local Public Health authority.

During the 2020-2021 flu season, it is more important than ever to reduce your risk of influenza-related health complications, so that healthcare providers are not overwhelmed during the pandemic.

The National Advisory Committee on Immunization (NACI) Recommendations 2020-2021 Flu Season

The National Advisory Committee on Immunization (NACI provides annual recommendations to the Public Health Agency of Canada regarding the use of seasonal influenza vaccines. 

Summary of NACI recommendations for the use of influenza vaccines for the 2020–2021 influenza season

NACI continues to recommend influenza vaccination to anyone six months of age and older who does not have contraindications to the vaccine. Vaccination should be offered as a priority to people at high risk of influenza-related complications or hospitalization, people capable of transmitting influenza to those at high risk of complications, and others as indicated below.

People at high risk of influenza-related complications or hospitalization:

  • All pregnant women
  • Adults and children with the following chronic health conditions:
    • Cardiac or pulmonary disorders (includes bronchopulmonary dysplasia, cystic fibrosis and asthma)
    • Diabetes mellitus and other metabolic diseases
    • Cancer, immune compromising conditions (due to underlying disease, therapy or both, such as solid organ transplant or hematopoietic stem cell transplant recipients)
    • Renal disease
    • Anemia or hemoglobinopathy
    • Neurologic or neurodevelopmental conditions (includes neuromuscular, neurovascular, neurodegenerative and neurodevelopmental conditions and seizure disorders [for children, includes febrile seizures and isolated developmental delay], but excludes migraines and psychiatric conditions without neurological conditions)
    • Morbid obesity (body mass index [BMI] of 40 and over)
    • Children six months to 18 years of age undergoing treatment for long periods with acetylsalicylic acid, because of the potential increase of Reye’s syndrome associated with influenza
  • People of any age who are residents of nursing homes and other chronic care facilities
  • Adults 65 years of age and older
  • All children 6–59 months of age
  • Indigenous people

People capable of transmitting influenza to those at high risk:

  • Health care and other care providers in facilities and community settings who, through their activities, are capable of transmitting influenza to those at high risk
  • Household contacts, both adults and children, of individuals at high risk, whether or not the individual at high risk has been vaccinated, including:
    • Household contacts of individuals at high risk
    • Household contacts of infants less than six months of age, as these infants are at high risk but cannot receive influenza vaccine
    • Members of a household expecting a newborn during the influenza season
  • Those providing regular child care to children 0–59 months of age, whether in or out of the home
  • Those who provide services within closed or relatively closed settings to people at high risk (e.g. crew on a ship)


  • People who provide essential community services
  • People who are in direct contact with poultry infected with avian influenza during culling operations

To learn more, read the Summary of the NACI Seasonal Influenza Vaccine Statement for 2020–2021


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

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