What is the flu/influenza?
What is influenza?
Influenza is an infection of the lungs and airways caused by a virus. Various strains of influenza virus circulate throughout the world each year. In North America, influenza usually affects people between November and April.
The influenza virus often changes slightly. Most people who have had influenza will have some protection against the changed virus. The influenza virus passes from person to person by droplets when an infected person coughs, sneezes or talks. Airborne droplets can enter the body through the eyes, nose or mouth. The virus, contained in droplets, can travel 1 to 2 metres in the air. It can live on hard surfaces for 1-2 days; on cloth, tissue and paper for 8-12 hours; and on hands for 5 minutes. People develop symptoms of influenza from 1 to 3 days after becoming infected. They are contagious from the day BEFORE they have the first symptoms until 5 days after the symptoms start.
Symptoms of influenza include:
- sudden fever of 38.0°C (100.4°F) or higher
- dry cough
- aching body, especially head, lower back and legs
- extreme weakness and tiredness
Other symptoms can include:
- chills
- aching behind the eyes
- loss of appetite
- sore throat
- runny or stuffy nose
For people older than 75 with influenza, the temperature may be lower, for example 37.2°C (99.0°F). They may also experience vomiting, diarrhea or stomach pain.
Fever usually goes down and the person starts to feel better in 3 to 5 days. Tiredness and cough can continue for several weeks.
Influenza symptoms are different from those of a cold or gastroenteritis ("stomach flu").
Because the influenza virus is always changing, a new vaccine is created each year containing the three virus strains most likely to circulate. This means you need to be immunized yearly. The best time to be immunized is during October and the first half of November - just before the influenza season starts, because it takes 2 weeks for the vaccine to become effective. Even after influenza arrives in the community, it is not too late to get immunized.
The vaccine cannot cause influenza because the virus in the vaccine is killed. The vaccine is 70 - 90% effective in young, healthy people and protection lasts about 6 months. The vaccine is less effective for people with weakened immune systems, but if they are immunized, the illness will be less severe if they do become infected.
Since vaccine strains are selected 6 to 9 months before the start of influenza season, there is a slight chance the circulating strain may change before the season actually starts. The vaccine will NOT protect against other respiratory illnesses.
Important Links
Information on Influenza Vaccination and Vaccination Clinic Dates
For more information on influenza, refer to the Yukon Health Guide or visit www.ykhealthguide.org.