To learn about the flu clinics, clinic schedule, location of the clinics, and employer-based clinics go to the Influenza Clinic page.

What is Influenza?

Influenza is a respiratory illness caused by influenza viruses that affect the nose, throat and lungs. The peak time for influenza illness is November to April, which is called the flu season.

It is estimated that there are 20,000 hospitalizations and 4,000 deaths each year in Canada related to influenza.

Although complications occur mostly in high risk populations such as those with chronic medical conditions (e.g. diabetes, heart disease) or weakened immune systems, pregnant women, seniors or very young children, they can affect anyone. Complications of influenza illness can include worsening of chronic health conditions, pneumonia or ear infections.

How is Influenza spread?hand touching surface

Influenza is spread from person to person directly by coughing or sneezing or indirectly by touching surfaces that are contaminated with the virus such as phones, elevator buttons, door knobs, toys and unclean hands.

People infected with influenza are most infectious before symptoms appear and in the first three days of illness, but may still transmit infection for up to six days or longer in the elderly or people with weakened immune systems.

What are the symptoms of Influenza?

Symptoms of influenza include sudden onset of cough, generalized body aches, headache, fatigue and fever. Some people infected with influenza may also experience a stuffy nose, sore throat or sneezing.

Influenza is often confused with the common cold. The following table illustrates the main differences between Influenza and the Common Cold.

Symptoms Flu Cold
Fever Usually present, high (102°F - 104°F or 38°C - 41°C); lasts 3 - 4 days Uncommon
Headache Very common (can be severe) Uncommon
Aches & pains Common and often severe. Slight
Fatigue & weakness Starts early, can be severe, and can last up to 14 - 21 days Mild
Extreme exhaustion Very common at the start. Never
Stuffy nose Sometimes Common
Sneezing Sometimes Common
Sore throat Sometimes Common
Cough Common Mild to moderate, hacking cough
Complications Can lead to pneumonia or respiratory failure; can worsen a current chronic condition; can be life-threatening. Can lead to sinus congestion or earache

Who is most at risk for Influenza-related complications?

Although influenza-related complications can affect anyone, they occur most often in those at high risk. These individuals include:

  • Adults and children with underlying health conditions (e.g. heart and lung conditions, diabetes, asthma)
  • Adults and children with compromised immune systems (e.g. chemotherapy, HIV/AIDS, chronic steroid use)
  • Healthy pregnant women
  • Persons identified as morbidly obese
  • Residents of long-term care homes and other chronic care facilities
  • People >65 years of age
  • Children <5 years of age

Influenza-related complications can include: worsening of chronic medical conditions, sinus and ear infections, pneumonia, hospitalization, and death.

What should I do if I think I have influenza?woman in bed

  • Stay home until your symptoms begin to go away
  • Cover your mouth and nose with your arm or a tissue when coughing or sneezing. Throw the used tissue in the garbage immediately and use alcohol-based hand rub or wash your hands with soap and running water
  • Do not visit people in hospital, long term care homes, retirement homes, or other chronic care facilities
  • See your doctor or nurse practitioner if:
    • you don't start to feel better after a few days
    • your symptoms get worse
    • you are in a high-risk group and develop flu symptoms

How do I help to prevent getting sick with influenza?

  • Frequently use alcohol-based hand rub or wash your hand cleaning surfaceshands with soap and running water, especially before eating or preparing food and after blowing your nose or using the washroom
  • Get your flu shot - For more information about the flu shot check here
  • Clean and disinfect common surfaces and items frequently (e.g. phones, door knobs, keyboards)

Links and Resourcesman sneezing in his elbow

Ontario Ministry of Health and Long-Term Care

Public Health Agency of Canada

World Health Organization

U.S. Centers for Disease Control and Prevention

For Healthcare Professionals

Region of Waterloo Public Health Big Shot Challenge Influenza Immunization Toolkit

Region of Waterloo Public Health Respiratory Outbreak Manual for Healthcare Facilities

National Advisory Committee on Immunization annual Statement on Influenza Vaccine

Region of Waterloo Influenza Bulletins

Long Term Care and Retirement Homes Newsletter