Influenza (sometimes called the flu) is an infection of the nose, throat, and lungs (respiratory tract) that is caused by a virus. Influenza can happen any time during the year, but most cases happen in the winter months.
You may also hear influenza called flu, bird flu, or H1N1. All of these mean the same thing as influenza, and the information below applies to all of them.
Influenza is spread through the air. The virus gets in the air when someone with the disease coughs, sneezes, or even talks. People who breathe in the virus can get sick. It can also be spread by touching objects that have been coughed or sneezed on by someone with the virus.
Most people who get sick with influenza get better. The number of people who get sick with influenza is different year to year. On average each year, more than 12,000 people in Canada have to stay in the hospital because of influenza, and 3,500 die from it.
You have a higher risk of complications (serious health problems) from influenza if you:
Complications of influenza can include pneumonia (a type of lung infection), ear and sinus infections, and dehydration. Influenza can also make chronic medical problems (such as congestive heart failure, asthma, diabetes) worse.
The symptoms of influenza are:
Other symptoms may include feeling sick to your stomach (nausea), vomiting (throwing up), or having loose stool (diarrhea). These are more common in young children.
You can spread influenza (be contagious) the day before you have symptoms and for up to 7 days after symptoms start.
GI Illness (Stomach "Flu")
Influenza A or Influenza B viruses
Not caused by influenza virus
Many different kinds of viruses such as rhinovirus, adenovirus
Norovirus (or Norwalk-like viruses) is the most common, but there are many causes of stomach upset.
Getting the influenza vaccine every year protects against the strains of the virus going around that season
Getting the COVID-19 vaccine provides protection from the SARS-CoV-2 virus (also known as COVID-19)
Cannot be prevented by immunization
Involves whole body
Symptoms appear quickly
No. Symptoms appear gradually.
Chills, aches, pain
Runny or stuffy nose
Sometimes (especially children)
Shortness of breath
Loss of smell or taste
Current as of: August 17, 2022
Author: Provincial Immunization Program, Alberta Health Services
This material is not a substitute for the advice of a qualified health professional. This material is intended for general information only and is provided on an "as is", "where is" basis. Although reasonable efforts were made to confirm the accuracy of the information, Alberta Health Services does not make any representation or warranty, express, implied or statutory, as to the accuracy, reliability, completeness, applicability or fitness for a particular purpose of such information. Alberta Health Services expressly disclaims all liability for the use of these materials, and for any claims, actions, demands or suits arising from such use.