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Mount Sinai Hospital is a University of Toronto patient care, teaching, and research centre.
Mount Sinai Hospital is a University of Toronto patient care, teaching, and research centre.

Frequently Asked Questions

» What is Influenza?

Influenza is a virus, which causes respiratory tract infections (lungs, throat and nose). There are two types of influenza; influenza A and influenza B. In young, healthy people, influenza is not a serious infection, although people with it may feel miserable for several days. In people over the age of 65 years, and those with chronic heart or lung disease, it causes more severe symptoms and may be complicated by congestive heart failure, pneumonia, or an asthmatic attack. In elderly people with chronic illness, about 1 in 20 people may need to be admitted to hospital because of complications of influenza. Approximately 4,000 Canadians die every year from the complications of influenza.

Influenza season is an 8-12 week period in the winter that starts sometime between November and February.

» What are the Symptoms of Influenza?

The usual symptoms are fever, chills, sore throat, cough, sneezing, runny nose, headache, weakness, loss of appetite, and/or muscle aches and pains. People with influenza can be bedridden for a week or longer.

» How is it Transmitted?

Influenza is transmitted by droplet spread. When someone who is infected coughs or sneezes, the virus is released into the air and falls on anything within about 4 feet. Anyone close to them can become infected, by breathing in the virus. Depending on the type of material the virus can live on surfaces or objects such as tables, water taps, books or clothing for 8-48 hours. When people touch these objects/surfaces they could pick up the virus on their hands and infect themselves when they touch their mouth and nose.

» Who is at Risk?

There are approximately 7 million Canadians who are at increased risk for serious infection or death from influenza. They are all individuals with diabetes, HIV, cancer, renal disease, chronic heart and lung disease, people who are immunosuppressed (including transplant patients). Children 6 months to 18 years who are being treated long term with acetylsalicylic acid, all individuals 65 years of age and older and all residents of long term care facilities (nursing homes, homes for the aged or chronic care facilities) are also in the high risk groups.

» How can it be Prevented?

Influenza vaccine protects healthy people from getting influenza 85-90% of the time. In the elderly and those with chronic illness, influenza vaccine is very effective in preventing death and other serious complications of influenza, but only prevents about half of all disease. Influenza vaccine must be given yearly, and is recommended in Canada for all people 65 years of age and over, all people with chronic illnesses, and household contacts and caregivers of such people.

To prevent transmission by contact with contaminated objects it is important that people cover their mouths when they cough or sneeze. Frequent handwashing will also decrease transmission.

» How Safe is the Influenza Vaccine?

The influenza vaccine is very safe. The vaccine is a killed virus and CAN NOT cause influenza. If you become ill after being vaccinated it is just coincidence and is probably a "cold".

As with any vaccination, local reactions can occur. These include mild soreness, redness or swelling at the site. These may occur in about 1/4 of people who are vaccinated. Fever, headaches, loss of appetite or nausea, weakness and muscle pains occur infrequently.

» How do we treat Influenza?

Since influenza is a virus, antibiotics will not work to kill it. However, Amantadine is a medication that is very effective in preventing influenza in people who have been exposed to influenza A virus. It also reduces the severity of influenza if it is started within two days of the beginning of illness. It is not effective if started later. It is not effective against influenza B.

Amantadine is usually given in a dose of 100 mg twice per day to healthy people, but the dose must be reduced in the elderly and in people whose kidney function is not normal. It is available as capsules or as a suspension. It should not be given to people who are pregnant, people who have seizures, or people who are taking any of a group of drugs called phenothiazines. It has few significant side effects, but may cause dizziness, nausea or difficulty sleeping in about one in twenty people who take it.

» Are there any new Treatments for Influenza?

A new class of drugs called neurominadase inhibitors have been developed for treating and preventing infection by influenza viruses. They work against both influenza A and B. If given to healthy people within 36 hours of onset of illness, they shorten the length of time people are ill by about two days. If given to people who have been exposed to the virus they are very effective in preventing them from becoming ill and does not have side effects.

This document has been prepared for educational purposes by Margaret McArthur, RN, CIC

Should you have questions regarding individual health concerns or health care practices, please consult your physician or health care provider directly.

This website has been made possible through an unrestricted educational grant from Pfizer Canada Inc.
Copyright 1999-2007 Department of Microbiology, Mount Sinai Hospital, Toronto, Canada. All rights reserved.