Commonly known as “the flu,” influenza is a serious respiratory disease caused by a virus. 10-20% of Canadians are infected every year during flu season (November to April). It spreads easily through coughing and sneezing, as well as through direct contact with surfaces contaminated by the flu virus. While some symptoms may be cold-like, the flu can be far more serious, causing fever, chills, cough, sore throat, headache and body aches. Although the fever may go away on the second or third day of illness, it may take up to six weeks to feel better. Most people recover fully, but the flu can lead to more serious illnesses such as pneumonia. Each year in Canada, approximately 20,000 people are hospitalized and 4,000 die due to influenza and its complications. Complications are more common in young children, the elderly, and those who have chronic medical conditions.
THE INFLUENZA VACCINE
Vaccination is the most effective way to prevent influenza. Other steps include: wash your hands frequently; avoid touching your eyes, nose and mouth with unwashed hands; cover your cough and sneeze; and stay home when you are sick.
The Ontario Ministry of Health and Long Term Care provides free flu vaccine for all those over 6 months of age who live, work, or attend school in Ontario. The vaccine is considered safe during pregnancy and breast-feeding.
Each year there is a new vaccine to protect against the influenza virus strains that are expected in the coming influenza season. As per the World Health Organization (WHO) recommendations, the vaccine for 2016-2017 can protect against the equivalent strains of A/California/7/2009(H1N1)pdm09-like, A/Hong Kong/4801/2014 (H3N2)-like, and B/Brisbane/60/2008-like flu viruses. Even if the strains have not changed, getting influenza vaccine every year is necessary to maximize protection.
Protection from the vaccine is achieved two weeks after the injection and may last six months or longer. With a good match between the vaccine and the circulating strain of virus, the vaccine is 80% effective in preventing influenza in healthy adults. For children, the vaccine is 60-80% effective. For those who receive the vaccine and still get the flu, it is usually milder than it would have been without the vaccine.
WHO SHOULD NOT GET THE INFLUENZA VACCINE?
• Infants under 6 months of age
• Anyone who has a severe allergy to eggs (require supervision in allergist office)
• Anyone allergic to chicken proteins, neomycin, kanamycin, formaldehyde, polysorbate 80 or CTAB
• 9cetyltrimethylammonium bromide) (for Agriflu)
• Anyone allergic to formaldehyde, sodium deoxycholate, sucrose and thimerosal (for Fluviral)
• Anyone who has had a serious allergic reaction to a previous dose of the flu vaccine
• Anyone with a history of Guillain-Barre Syndrome within 6 weeks of a previous flu vaccine
• Anyone with a history of Oculo-Respiratory Syndrome following receipt of influenza vaccine, where it was severe enough to result in hospitalization
• Anyone who is ill and has a fever, until he/she is feeling better
Flu shots are safe and well-tolerated. The vaccine (Agriflu, Fluviral) cannot cause influenza because it does not contain any live virus. Most people have no reaction to the vaccine, or mild reaction that last 1-3 days such as:
• Soreness, redness and swelling at the injection site
• Low grade fever, headache, and muscle aches; extra rest, fluids, and acetaminophen (Tylenol) will help ease these symptoms
Severe side effects and allergic reactions are very rare. Fewer than 1 in 20 people may have Oculo-Respiratory Syndrome (ORS). Symptoms of ORS include red eyes and a cough and/or sore throat and/or hoarseness. In most cases, the symptoms are mild and disappear within 48 hours. Guillain-Barre Syndrome (GBS) is a rare condition that can result in weakness and paralysis. It most commonly occurs after infection but in rare cases can also occur after some vaccines. Most patients recover fully. Your chance of developing GBS as a result of the flu shot is one in a million.
At the time of year that the vaccine is given, many viruses are making people sick. Infection with these viruses may be mistaken for a reaction to the flu vaccine. The primary reason to get a flu shot is to protect yourself from health effects related to flu. However, by getting a flu shot, you will also help protect other Canadians and reduce the burden on the health care system.