Flu (influenza): Prevention and risks
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How the flu spreads
The flu is an infection of the nose, throat and lungs. It's mainly caused by 2 types of flu viruses:
- influenza A
- influenza B
It spreads very easily from person to person. A person can spread the flu virus to others even before they notice any symptoms.
They release infectious respiratory particles (the virus) into the air during actions like:
- coughing
- sneezing
- talking
- breathing
You can get the flu if you breathe the virus in, or if the virus comes into direct contact with your eyes, nose or mouth. For example, if someone coughs or sneezes on you.
People may also have the virus in infectious secretions like their saliva or mucus. You can get the flu if you touch:
- their saliva or mucus
- surfaces and objects contaminated by them, then touch your eyes, nose or mouth before cleaning your hands
Surfaces and objects that are often touched by others are more likely to have infectious particles or secretions, such as:
- phones
- door handles
- light switches
- elevator buttons
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Preventing the flu
Vaccination
The flu vaccine (flu shot) is the best way to prevent the flu. Most people don't have any side effects. Severe reactions are very rare.
You can't get the flu from the flu vaccine.
Almost everyone 6 months of age and older should get the flu vaccine.
Talk to a health care provider or your local public health unit if you have questions about the flu vaccine.
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Personal protective measures
In addition to getting the flu vaccine, you can reduce your risk of getting or spreading the flu by:
- staying home when you're sick
- wearing a well-fitting mask
- opening windows and doors when possible to improve indoor air ventilation
- washing your hands often with soap and water for at least 20 seconds
- if unavailable, use a hand sanitizer containing at least 60% alcohol and rub your hands together for 20 seconds or until dry
- coughing and sneezing into a tissue or your elbow instead of your hand
- avoiding touching your eyes, nose or mouth with unclean hands
- cleaning and disinfecting surfaces and objects regularly that are often touched by others
Learn more:
- Vaccine safety and possible side effects
- Vaccine safety: Immunization and vaccine awareness poster
- Clean your hands to help reduce the spread of infectious diseases
- Respiratory infectious diseases: How to reduce the spread with personal protective measures
Risks of getting the flu
In Canada, your risk of getting the flu is higher in the late fall and winter (flu season).
It's lower during the rest of the year.
Pandemic flu
Pandemic flu is different from both seasonal flu and COVID-19. Pandemic flu is a rare event caused by a new flu virus. Humans would have little or no immunity to a new flu virus because they haven't been exposed to it before. Because of this, it would easily spread between people.
It's impossible to predict when the next flu pandemic will happen and what its impact will be. It's important to be prepared for different situations.
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Who is most at risk
Everyone is at risk of getting the flu. The flu is among the 10 leading causes of death in Canada. Every year in Canada, the flu causes about:
- 12,200 hospital stays
- 3,500 deaths
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People with health conditions
You're at a higher risk of flu-related complications if you have a health condition, such as:
- kidney disease
- diabetes or other metabolic diseases
- anemia or other blood disorders and diseases
- neurological or neurodevelopmental conditions
- cancer or other conditions that compromise the immune system
- severe obesity (body mass index of 40 kg/m² and over)
- heart or lung disorders
- children up to 18 years of age undergoing treatment for long periods with acetylsalicylic acid (ASA)
Getting the flu can also worsen the symptoms of some of these health conditions.
Older adults and younger children
You are at higher risk of getting the flu if you're 65 years of age and older.
Your immune system changes with age and this can make it harder for your body to fight off infections. You're more likely to have severe outcomes from the flu, such as hospitalization or death.
Children under 6 years of age are also more at risk of getting the flu. Their immune systems are still developing the ability to fight off serious infections.
People in group living settings
People who live in a nursing home or other long-term care facility are more at risk of getting the flu.
The flu spreads quickly in communal living spaces. Residents of such settings are more likely to have chronic health conditions. These conditions can get worse or increase the risk of severe outcomes of getting the flu.
People who are pregnant
During pregnancy, your body goes through many changes that can affect your immune system, heart and lungs. These changes can make it harder to fight off infections. Pregnant people, fetuses and infants are at higher risk of severe disease from flu.
If you get the flu vaccine during pregnancy, you pass on protection to your baby. This is especially important as babies younger than 6 months can't get vaccinated against the flu. Getting your flu vaccine can help protect your baby from the flu, both before and after birth. This is when they're at highest risk of complications.
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Indigenous Peoples
The flu vaccine is particularly recommended for Indigenous Peoples based on studies showing more severe outcomes.
People who may increase the risk of spreading flu
Some people are more likely to spread the flu to those at higher risk of complications. These people include:
- caregivers
- health care providers
- child care provider to children less than 6 years of age
- people living with someone at higher risk, such as households expecting a newborn during flu season
- people providing services in closed or relatively closed settings to people at higher risk, such as:
- workers in long-term care facilities
- a crew on a ship
- people providing essential community services
- people in direct contact with poultry infected with avian influenza (bird flu) during culling (depopulation) operations
- the flu vaccine doesn't protect against avian influenza but may reduce the risk of being infected with both seasonal flu and bird flu
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