Influenza is an infection of the upper airway known as the flu. It is caused by a strain of the influenza virus. There are many types of these viruses but the two that most often infect humans include:
Each year the flu spreads around the world. It spreads most often from person to person. Someone who is infected releases the virus through droplets in sneezes or coughs. Others inhale these droplets, then become sick. The virus can also land on a surface. Someone can become infected if they touch the surface then touch their mouth or nose. For most, the flu will cause fever, aches, fatigue, coughing, stuffiness, and sore throat. Some people have a higher risk of a severe infection. It may lead to hospital care. Risk factors for severe complications include:
This vaccine uses pieces of the virus. These pieces cannot cause an infection but will show the immune system what the virus looks like. The body will then be able to fight the virus before an infection starts. Full protection can start within a few days. There are different types of flu vaccine:
A doctor will help to find which shots will be best for each person. Age and overall health will play a role in the decision.
The flu virus changes each year so, the shots need to be given each year. There are many types of the flu virus. Researchers will pick the 4 most likely types of flu to spread that flu season. It is possible to be infected with a type of flu virus that was not included in the vaccine. However, the illness is often less severe.
The Centers for Disease Control and Prevention (CDC) recommend that anyone aged 6 months and older should get a flu shot. It should be done every year.
It takes about 2 weeks for the vaccine to have full effect. The best time to get a flu shot is as soon as the shot is available. This will protect you before the flu comes to the community.
The flu shot is safe for almost all people. There is a small risk of serious problems such as severe allergic reaction.
Minor side effects associated with the flu shot include:
Minor side effects associated with the nasal spray vaccine include:
There is a higher risk of problems from the flu shot in people with 1 or more of the following:
The following people should not get the nasal spray:
Habits that may decrease your exposure to the flu virus include:
To reduce spread of flu to others, cover your nose and mouth when you cough or sneeze. Use your elbow or a tissue as cover.
Get a flu shot if you have not already done so. The more people who have had flu shots the safer the community will be. Viruses will have a harder time passing from person to person if most have had the flu shot. Follow other steps like washing your hands even if you have had the flu shot.
WHERE CAN I GET MORE INFORMATION?
Centers for Disease Control and Prevention
Public Health Agency of Canada
US Food & Drug Administration
Key factors about influenza vaccine. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/flu/prevent/keyfacts.htm#match. Accessed May 10, 2019.
Influenza in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/influenza-in-adults. Accessed May 10, 2019.
Influenza in children. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/influenza-in-children. Accessed May 10, 2019.
Seasonal influenza vaccines in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/seasonal-influenza-vaccines-in-adults. Accessed May 10, 2019.
Seasonal influenza vaccines in children. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/seasonal-influenza-vaccines-in-children. Accessed May 10, 2019.
Seasonal influenza vaccines in the elderly. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/seasonal-influenza-vaccine-in-older-adults. Accessed May 10, 2019.
Last reviewed September 2020 by
EBSCO Medical Review Board
Chelsea Skucek, MSN, BS, RNC-NIC
Last Updated: 8/7/2020