I have heard a lot about ‘human swine influenza' or ‘ novel A(H1N1) influenza' - what is this virus and what does A(H1N1) mean?

This is a new human influenza virus first seen in Mexico in March 2009 and which is now spreading in other countries, particularly in North America.  The virus has genetic characteristics previously seen in swine (pig) viruses and it is thought to have originated when a pig virus mutated and began to spread among humans.   The H and N numbers are a way of classifying different groups of type A influenza viruses into ‘subtypes' or families.

How does this new influenza virus spread?

The new virus spreads in the same way as normal seasonal influenza; that is airborne infection due to infected people coughing or sneezing, or by hand to mouth/face transmission by contact with contaminated surfaces. Good cough and sneeze etiquette, good hand hygiene and staying at home when you are unwell with influenza-like symptoms are important to help limit the spread of any influenza virus.

Will the influenza vaccine that is currently available protect me against this new virus?

Although there is a virus of the A(H1N1) family in our current vaccine, because the new virus is very different from it the vaccine is not expected to provide any significant protection against infection.  However, there is a slight possibility that the vaccine may ‘prime' your immune system and help you to respond to infection.

What is meant by an 'influenza pandemic'?

The World Health Organization (WHO) has formulated a plan which defines six phases for Pandemic Influenza Preparedness and Response, with ‘Phase 6' being a declared pandemic.  The world has been at ‘Phase 3', a moderately heightened level, for some time due to the ongoing human cases of H5 avian influenza. In response to the new 'swine flu' virus, the WHO raised the level first to ‘Phase 4' (medium to high chance of a pandemic), then to ‘Phase 5' (high to certain chance of a pandemic), before declaring 'Phase 6'. At this time, the overall severity of the influenza pandemic is considered to be moderate. The WHO is now referring to the current pandemic as "pandemic (H1N1) 2009".

If the seasonal influenza vaccine won't give me significant protection why should I bother being vaccinated?

While it seems likely that the new virus will continue to spread there is no guarantee that it will be present in Australia this winter.  On the other hand, we can almost guarantee that virus strains covered by the vaccine will be present in Australia and cause significant illness. Many people forget that the ‘normal' seasonal influenza causes serious illness in Australia each year - in fact it is estimated to cause around 2,500 deaths annually.  Thus, vaccination against seasonal influenza is very important, particularly for ‘high-risk' individuals who are at risk of serious complications from influenza.

Who is most at risk of serious complications from influenza?

There are well defined risk categories for seasonal influenza (Australian Immunisation Handbook, 9th Edition, 2008), although in the event of a pandemic it may be necessary to revise these.  More people are at risk of serious complications from seasonal influenza than you may think.  It is extremely important that anyone who falls into one or more of the following groups get vaccinated against influenza every year because of this risk:
-    Older adults (65 years and above)
-    People with underlying medical conditions such as heart, kidney and lung disorders, diabetes and immune problems
-    Aboriginal and Torres Strait Islanders aged 15 or older
-    Pregnant women (including pregnant women who are in the first trimester at time of vaccination)
-    Anyone in close contact with any of the groups listed above - this includes household contacts and healthcare workers

Recently there has also been growing concern regarding the severity of influenza in children under five years of age, so parents may also which to consider vaccinating children in this age group also. Many other people may choose to get vaccinated against influenza, and this is supported by the Australian Guidelines.

Will there be a vaccine against the new ‘swine influenza' A(H1N1) strain for this winter?

Influenza vaccine production has a long lead-time and it would be of the order of three months before any vaccine could be available.  World Health Organization (WHO) laboratories and pharmaceutical companies are currently undertaking all of the essential steps for vaccine production.  When these have been completed a decision to proceed will depend on recommendations from the WHO and national governments, which will be based on further spread and severity of the disease.

When should I be vaccinated?

A seasonal influenza vaccine is available now and is designed to protect you against the most commonly circulating strains of influenza (not the new A(H1N1) strain circulating overseas).  If you wish to protect yourself against seasonal influenza, speak with your GP now, ahead of outbreaks that usually begin as early as June and peak in around August or September.  It is important to remember that children under nine years of age who are being vaccinated for the first time will require two vaccine doses one month apart.