Australian Health Management Plan for Pandemic Influenza

2.4 Protecting the population using vaccination

Influenza Vaccines

Seasonal influenza vaccines refer to vaccines, updated yearly, that protect against seasonal (winter) influenza viruses. These vaccines will not provide adequate protection against a pandemic virus.

Candidate pandemic vaccines are based on a viral strain that is thought to have ‘pandemic potential’ for example the H5N1 strain that is currently circulating. The virus strain from which these types of vaccines are made is unlikely to be an exact match to the strain that eventually causes the pandemic. If these vaccines are used they may reduce the severity of illness in those who become infected, or prevent infection in some people, but not to the extent of a customised pandemic vaccine. They may also ‘prime’ the immune system—potentially shortening the amount of time it takes to mount an immune response to the customised vaccine, and possibly decreasing the number of doses of customised vaccine that are required.

Candidate pandemic vaccines are unlikely to offer full protection and indeed would only be useful if the vaccine and the pandemic strain belong to the same influenza subtype. The advantage of these vaccines is that they can be made and stockpiled ahead of time and hence would be available for use from the DELAY phase, some months before a customised pandemic vaccine would be available.

Customised pandemic vaccine is a specific, customised vaccine against the pandemic virus based on the actual pandemic viral strain. As such, production of this vaccine can only begin once the actual virus has emerged in the DELAY phase.

It is likely that customised pandemic vaccines will provide a significant level of protection against both infection and the development of severe illness. The exact level of protection and particularly effectiveness of the vaccine in different groups (for example, the elderly, children and people with severe medical conditions) will not be known until the pandemic has begun and rapid studies are performed.
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How long until a customised pandemic vaccine becomes available

If production of a customised pandemic vaccine starts as soon as the pandemic virus has emerged it could take several months for the first doses of vaccine to become available in Australia and up to 12 months before there is enough vaccine for all Australians to receive a full course, and develop immunity.

This reinforces the importance of the measures to slow the arrival and spread of pandemic influenza in Australia. For every week we can delay the entry or reduce the spread of infection, we will be a week closer to being able to protect the whole population through vaccination.

Ways in which vaccines against pandemic influenza could be used

Australia has a small stockpile of an H5N1 candidate pandemic vaccine which may be used in the DELAY phase should the emerging virus be a H5 subtype.

The government will assess the risks and the benefits of a customised pandemic vaccine when it is developed and will use it in the most effective manner. If appropriate the government aims to provide a full course of a customised pandemic vaccine to every Australian as quickly, safely and as effectively as possible. It will be necessary for governments to prioritise the distribution of initial doses of the vaccine.

Prioritising the distribution of stockpiled candidate vaccine and the initial doses of the customised pandemic vaccine would be a whole of government decision that would be made at the time, taking into account:

• the needs of the health sector and other critical infrastructure to maintain societal functioning
• the infectiousness of the pandemic virus
• the impact of disease on different population groups.

The Australian Government is actively considering issues related to distribution, allocation and administration of pandemic vaccines and is in consultation with state and territory governments regarding these issues.
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Phase snapshot: Protecting the population by using vaccines

PHASE	HEALTH ACTION
ALERT	Prepare policy, infrastructure, processes Purchase and stockpile candidate pandemic vaccine Make arrangements for future production and purchase of customised pandemic vaccine
DELAY	Consider use of candidate pandemic vaccine from stockpile and implement according to whole of government decision Implement customised pandemic vaccine production (once the pandemic virus is available) Prepare to deliver vaccination services to priority groups then whole population
CONTAIN	Continue customised pandemic vaccine production (and distribute when available)
SUSTAIN	Continue customised pandemic vaccine production and distribution Evaluate effectiveness of vaccination
CONTROL	Continue customised pandemic vaccine production and distribution
RECOVER	Get ready to re-implement measures if a subsequent wave is imminent Monitor drift of viral strains
Linked document	Vaccination Annex (under development)

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This information is current for 03 September, 2010
This information was issued on 05 December, 2008