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Bird Flu Vaccines
and Anti-Virals Info |
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Vaccination Data
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Anti-virals Data
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Start of Pandemic
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Vaccines
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The World Health Organization, the Public Health Agency of Canada, and the
Ontario Ministry of Health and Long-Term Care all agree that a monovalent
influenza vaccine will be a powerful tool for reducing disease, death and
societal disruption during an influenza pandemic. Antiviral medications will
also play an important role in preventing and treating influenza illness during
a pandemic.
During a pandemic, Toronto Public Health will serve as the primary coordinator
for the distribution and administration of vaccine and distribution of antiviral
medications in the City of Toronto. As it is likely that the supply of both
antiviral medications and vaccine will be limited during a pandemic, the
distribution of both will be controlled by the Ontario government.
Recommendations for priority groups for vaccination and antiviral medications
for both treatment and prophylaxis have been established in the Canadian
Pandemic Plan and are further elaborated on in the Ontario Pandemic Plan.
The Government of Canada has secured a contract with a Canadian supplier for
pandemic influenza vaccine. Once the pandemic influenza strain is identified,
the Pandemic Influenza Committee (PIC) will ask Canada's vaccine supplier to
initiate vaccine development, testing and production. This process is estimated
to take approximately 4 to 6 months (before this anti-virals will be used to
stop the spread of the virus). The manufacturer is under contract to produce and
distribute 8 million doses of vaccine per month once production is in full
swing. Toronto Public Health (TPH) will receive a portion of the total doses of
vaccine available in Canada per month based on population and the number of high
risk individuals in Toronto.1
The plan for distribution and administration of pandemic vaccine is divided into
2 parts:
- Part I: Vaccine distribution and/or administration to Priority
Groups 1, 2 and 3 as identified by the MOHLTC.
- Part II: Vaccine distribution and administration to the general public,
Priority Groups 4, 5 and 6 as identified by the MOHLTC.
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Antiviral Medications
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Antiviral medications work by disrupting the replication of the influenza virus.
They can be used to treat individuals showing early signs and symptoms of
influenza and have been shown to reduce the length and severity of
influenza-related illness. Antiviral medication can also be used to prevent
illness when given to those exposed to influenza. Since vaccine production
requires up to 4 to 6 months from the identification of a novel influenza virus,
antiviral medication may be used to prevent influenza illness early in the
pandemic. Antiviral medication will be used throughout the pandemic to treat
individuals with influenza illness. Both the Canadian and Ontario governments
have begun stockpiling antiviral medications for use during a pandemic.
There are two types of antiviral medication used to prevent influenza A
infection and treat influenza illness. The two types are: M2 ion channel
inhibitors (amantadine and rimantadine) and neuraminidase inhibitors
[oseltamavir (Tamiflu) and zanamivir (Relenza)]. Amantadine and rimantadine
blocks the functioning of the influenza M2 protein in influenza A viruses. It is
taken orally but has some limitations. Some influenza viruses are resistant to
Amantadine and those that are not can become resistant quickly once infected
individuals begin to take this medication. The neuraminidase inhibitors such as
oseltamivir (Tamiflu®) and zanamivir (Relenza®) are the other antiviral
medications that will be useful in a pandemic. They work by blocking a key
protein that helps both influenza A and B viruses replicate. The main limitation
of zanamivir (Relenza®) is the inhaled route of administration and rare side
effects observed in people with asthma and COPD. If resistance to oseltamivir is
observed, it will be imperative to have a backup option. Zanamivir could be this
option.
Antiviral medications are effective in reducing duration of influenza illness if
administered within two days (48 hours) of onset of symptoms. The neuraminidase
inhibitors also reduce the complications of influenza infection such as
secondary bacterial pneumonia and hospitalization. Antiviral medication will
most likely be used to treat those with severe influenza illness during a
pandemic, those sick enough to require hospital care. Although, the
effectiveness of antiviral medications against a novel pandemic virus is unknown
it is likely that the neuraminidase inhibitors will reduce the severity of
influenza illness caused by a pandemic.
Early in a pandemic, stockpiled antiviral medication will be used to prevent the
spread of the new influenza virus from cases that arrive with the infection from
elsewhere. This will require rapid identification of contacts of these initial
cases and prompt distribution of antiviral medication to these contacts. Since
SARS, TPH has substantially strengthened its relationship with hospitals and put
into place a surveillance system for febrile respiratory illness (FRI). This
system will be valuable in detecting initial cases of influenza once a novel
pandemic virus has been identified with the capability to be transmitted from
human to human.1
The MOHLTC has identified priority groups for the use of antiviral medications
for both treatment and prophylaxis. Please see the tables on pg. 131 and 132.
Priority groups for treatment have been defined as:
Group 1 - persons hospitalized for influenza
Group 2 - ill health care workers and first responders/emergency service
providers
Group 3 - ill high risk persons in the community
Group 4 - ill high risk residents in institutions
Priority groups for prophylaxis have been defined as:
Group 1 - front line health workers and key decision makers
Group 2 - remaining health care workers
Group 3 - emergency/essential services workers
Group 4 - high risk residents of institutions
Group 5 - persons at high risk of being hospitalized for illness other than
influenza
Group 6 - persons at high risk in the community
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This site has been made possible through an unrestricted educational
grant from
Roche Canada Inc.
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