Tips at-a-glance | General Information | Influenza Vaccination
What are the symptoms
typical of the "flu"?
The term "flu" is often applied to almost anything that makes us
feel unwell. However, the "flu" is a specific infection caused by
influenza viruses and is usually a more severe illness than the common cold,
which is caused by other respiratory viruses. Influenza typically has a sudden
onset with headache, chills and cough followed rapidly by a fever, appetite
loss, muscle aches, and tiredness. On the other hand, cold symptoms are limited
to the upper respiratory tract with runny nose, sneezing, watery eyes, and
throat irritation. Gastrointestinal symptoms, such as nausea, vomiting or
diarrhea, can sometimes accompany influenza, especially in children, but are
rarely prominent. The term "stomach flu" is often incorrectly used
to describe gastrointestinal illness that is due to other causes.
How long is a person
infectious once he/she gets influenza?
The period of communicability or infectiousness is usually 3 to 5 days from
the onset of symptoms in adults and up to 7 days in young children.
When does the influenza
season begin in Canada?
There may be local outbreaks of influenza anytime during the fall with definite
outbreaks being common from November or December through April and May.
Why is influenza a
winter disease?
Technically, influenza is not bound by seasons, and can occur all year round
in tropical climates. But in temperate climates, like those found in Canada,
influenza is predominantly a winter disease. The reasons for winter predominance
of influenza occurrence have not been positively identified; however, it is
possible that the transmission of the viruses are facilitated by people congregating
indoors more during the winter or drier indoor air which may help the viruses
to survive longer. It is recognized that, in instances where many people from
different parts of the world are confined together, like on a cruise ship
or an airplane, the chances of being infected increase. An example of this
was the out-of-season outbreak on Alaskan cruise ships last summer.
Are there any means
of preventing infection?
Hygienic practices such as hand washing, especially after contact with persons
who may have the flu and after handling soiled tissues may, to some degree,
reduce the risk of being infected. However, the only proven effective method
of prevention is vaccination, preferably 2 weeks before the beginning of the
active "flu" season.
Are there other viruses
that can cause similar illnesses?
Yes. Respiratory infections other than common cold viruses may occur. Viruses
such as respiratory syncytial virus (RSV) and parainfluenza viruses can cause
infections which may be mistaken for the "flu" with similar symptoms
including fever, cough, and sore throat. These viruses primarily affect young
children but can re-infect adults. They tend to be present in varying degrees
every winter.
Is there anything you
can do once you have the "flu"?
For most individuals, treating the symptoms is the only recourse, that is,
fluids and rest for the 5 to 7 days that symptoms might last. Recently, new
medications have become available in Canada, specifically designed to treat
the "flu". These drugs may decrease the length of time that symptoms
persist by an average of 1 to 1.5 days if started within 48 hours of illness
onset.
How many types of influenza
virus are there?
There are two main types: influenza A and influenza B. Influenza A usually
causes more severe illness than influenza B and can result in pneumonia, hospitalization
or even death, especially in the elderly and those with chronic illnesses.
How does influenza
travel the world so quickly?
The "flu" virus is transmitted from person to person very efficiently
through droplets of saliva or phlegm that travel through the air, usually
propelled by the action of coughing or sneezing. This mode of transportation
is especially effective in confined or enclosed environments, typically experienced
by Canadians in the winter months. It can also be passed through surface contact,
for example touching an object like a doorknob or telephone receiver that
has been recently handled by an infectious person. Air travel can help the
virus move quickly from country to country, and subsequently, around the world
in a very efficient manner.
How do you know what
will be the predominant strain?
The Laboratory Centre for Disease Control (LCDC) Health Canada collaborates
with a network of laboratories across the country to identify and characterize
strains of influenza. This network can determine what are the prominent strains
and use this information to predict future "up and coming" strains
for inclusion into future vaccines.
How many deaths due
to influenza occur in Canada each year?
The number of deaths due to influenza or its complications during the "flu"
season will vary each year, but is estimated to be approximately 500 to 1,500
per season.
How many influenza
infections might we have in Canada in one season?
In 1991-1992 it was estimated that half of those Canadians under age 15 years
had been infected with influenza A virus during that season and that about
26% of Canadians of all ages (or about 7 million) had influenza A virus infections.
What was the most common
influenza strain in the 1998-1999 season?
Of the 184 viruses isolated and submitted for strain characterization to the
LCDC during the 1998-1999 influenza season, 85% were influenza type A. The
predominant strain was A/Sydney/5/97-like (H3N2).
Is the influenza A
strain expected in the winter of 1999-2000 likely to cause a severe epidemic
and is this strain more potent than other influenza strains?
The influenza A virus expected to be active in the 1999-2000 influenza season
is similar to the influenza A/Sydney/5/97-like strain that was active last
winter. This strain is included in the vaccine for the 1999-2000 influenza
season. The influenza A/Sydney/5/97-like strain is not expected to be any
more potent than previous strains, and the usual amount of infection is expected
to occur this winter in those not protected by vaccine.
What is Reye's syndrome?
Reye's syndrome is a rare complication in children who have taken salicylates
(aspirin) and are infected with influenza virus, or the virus that causes
chickenpox. It specifically affects the central nervous system and the liver
and can result in death. Children and teenagers with the "flu" should
avoid aspirin unless specifically directed by a physician.
Are all new influenza
strains isolated in China?
Some new strains come from China, however, they may also arise in different
countries. For example, the predominant strain during the 1997-1998 and 1998-1999
seasons was influenza A/Sydney/5/97 (H3N2)-like, which means that it was first
isolated in Sydney (Australia) in 1997.
Part Two: Influenza Vaccination
How do they decide
what "flu" strains to put into a vaccine?
A global network of laboratories isolates and identifies specific influenza
viruses as they appear. In Canada, this network involves regional, provincial/territorial
and federal laboratories. The viruses identified are reported to the three
World Health Organization (WHO) Collaborating Centres on Influenza. The vaccines
are then updated to include the most current influenza virus strains that
have the greatest likelihood of causing widespread and severe illness.
What are influenza
vaccines made of?
Current influenza vaccines are made of dead influenza virus, which has been
further treated to break up the virus into purified components.
How is it made?
Every year, the WHO makes a recommendation regarding which strains should
be included in the influenza vaccination. Based on that recommendation, the
global network of laboratories provide vaccine manufacturers with the seed
strains they need to produce the vaccine. Influenza vaccine viruses are initially
grown in fertilized hens eggs. The virus is then extracted from the egg, inactivated
and "split" into parts, that are then used to make the vaccine.
What are the components
of the influenza vaccine for 1999-2000?
The National Advisory Committee on Immunization (NACI) has recommended that
the vaccine contain the following three components: A/Sydney/5/97 (H3N2)-like
strain, an A/Beijing/262/95 (H1N1)-like strain, and a B/Yamanashi/166/98-like
strain.
How does vaccination
protect you?
After vaccination, the body's immune system produces antibodies against the
inactivated virus in the vaccine. If you are exposed to the real virus, the
antibodies prevent the infection or reduce the likelihood of severe illness
should infection occur.
Who should receive
the influenza vaccine?
Influenza vaccine is recommended for people who are at high risk for developing
serious complications as a result of influenza, including:
The vaccine is also recommended for people who are capable of transmitting influenza to those at high risk (health care workers and household contacts) and those providing essential community services. Anyone older than 6 months who wish to protect themselves against influenza should also consider vaccination even if they are not in a high risk group.
Why is it recommended
that influenza vaccine be taken every year?
The antibodies produced in response to an influenza vaccine decline over time
and may be too low to offer adequate protection for the following year. In
general, influenza antibodies from vaccination only lasts 4-6 months. As well,
influenza viruses continually undergo changes, as a result of a mutation in
their genes and immunity acquired as a result of previous influenza infections
or the previous year's vaccination would not necessarily protect against subsequent
infections. As the influenza viruses change, the vaccine has to be updated
on a yearly basis to include the most current strains.
Is it too late to get
an influenza vaccination in January?
No. Active "flu" season begins in November and ends in May. Getting
vaccinated at anytime between these months would still be useful to protect
against infection; however, you should consult with your physician or local
public health authority.
Is it useful to get
a vaccination if you are already coming down with the "flu"?
Yes. The vaccine will not help with the current infection but could help protect
against other influenza strains which may also be present in a given year.
Is it possible to become
infected even if you have been vaccinated?
Yes. It is possible to become infected after vaccination, particularly in
older adults whose immune systems may be less effective in responding to the
vaccine. However, for those who still get infected after vaccination, the
disease is likely to be less severe and less likely to result in hospitalization
or death.
What factors affect the success of influenza vaccine?
How many vaccine doses
have been distributed in Canada in recent years?
The number of vaccine doses distributed in Canada by manufacturers is estimated
to be:
1998 - 5.1 million
1997 - 5.3 million
1996 - 4.3 million
1995 - 4.2 million
1994 - 4.0 million
Is there anything other
than vaccine that can be used to control influenza?
Amantadine, an antiviral medication, can be used to protect people who have
been in contact with an infected person or for individuals who may respond
poorly to influenza vaccination (for example, the elderly). Amantadine is
most useful in certain situations, such as outbreaks of influenza in nursing
homes. It is not effective against influenza B virus. A new class of antiviral
medications, the neuraminidase inhibitors, is able to inhibit both influenza
A and B. One neuraminidase inhibitor, zanamivir (Relenza), has recently been
given a Notice of Compliance with Conditions, allowing it to be sold in Canada
for the treatment of influenza. Zanamivir, an inhaled medication, has been
shown to reduce the duration (by an average of 1 to 1.5 days) and severity
of "flu" symptoms when taken within 48 hours of the onset of symptoms.
Zanamivir is not currently licensed in Canada, for the prevention of influenza.
Antiviral medications should not replace influenza vaccine for the prevention
of influenza.
Need more information on parenting? Your Employee Assistance Program (EAP) can help with a child to elder care resource and referral service that is geared toward enhancing the quality of family life. Call your Employee Assistance Program (EAP) to see if you are eligible for the child to elder care resource and referral service at 1 866.468.9461 or 1.800.387.4765.
© 2005 WarrenShepell