What is influenza?

• Influenza is a serious, often debilitating illness which the affects the whole body.
• Influenza symptoms include fever, headaches, muscle aches and pains.¹ Children's symptoms may also include nausea, vomiting and diarrhoea.²
• Influenza can cause serious illness, particularly in young children, older adults and people with underlying medical conditions.
• Many people confuse the common cold with influenza; however, colds are much less severe.

How serious is seasonal influenza?

• Each year an estimated 2,500 Australians die from influenza and its complications.³
• The World Health Organization (WHO) estimates that worldwide 5-15% of the population are affected by influenza each year, there are between three and five million cases of serious illness and between 250,000 and 500,000 deaths.⁴
• In Australia it is estimated that influenza annually causes 18,000 hospitalisations and over 300,000 GP consultations.⁵

How contagious is influenza?

• Influenza is highly contagious, with children being a major transmitter of the virus.⁷ Studies have shown that influenza can survive for: 
   - An hour or more in the air in enclosed environments¹¹
   - More than eight hours on hard surfaces such as stainless steel and plastic¹²
   - Up to five minutes on hands after transfer from other surfaces¹²

Who is at particular risk of complications from influenza?²

• People at particular risk of severe complications from influenza are those with:
   - Heart conditions
   - Asthma and other lung conditions
   - Diabetes (type 1 and type 2)
   - Kidney problems 
   - Impaired immunity
• People ≥65 years of age, residents of nursing homes and other long-term care facilities, and Aboriginal and Torres Strait Island adults aged ≥15 years are also at increased risk of severe complications from influenza.
• People who care for or are in close contact with at-risk individuals, are also advised to protect themselves against influenza to avoid passing on the disease.
• Many otherwise healthy Australians who can not afford to get influenza, such as single parents, carers, those who are self-employed or people who can't afford to take any time off work.

How can you reduce your risk of catching influenza?

A new influenza vaccine with an updated formulation is produced every year, to ensure that Australians are given the best possible protection. The vaccine protects people against three strains of influenza which the WHO identifies as the most likely to cause outbreaks for that season.

• The 2009 Southern Hemisphere influenza vaccine contains the following three influenza strains:¹³
   - A/(H1N1): an A/Brisbane/59/2007 (H1N1) - like strain 
   - A/(H3N2): an A/Brisbane/10/2007 (H3N2) - like strain
   - B/Florida/4/2006 - like strain
• For most parts of Australia influenza vaccination is best carried out in the autumn, before serious outbreaks begin to occur.² The majority of infections occur between July-September.¹⁴
• In the far north of Australia influenza outbreaks can occur early in the year and vaccination should be practiced as early as possible.
• No vaccine is 100% effective. However, clinical trials have shown that influenza vaccination is very effective in protecting against the severe consequences of infection. In healthy adults the vaccine has been shown to be 70-90% effective in protecting against infection.²

What can you do if you fall ill with influenza?

• Influenza is highly contagious and can be spread for up to a day before symptoms appear and for five days afterwards.² Ways to avoid spreading influenza include: 
   - Wash your hands regularly 
   - Cover your nose and mouth when coughing or sneezing
   - Avoid physical contact with others 
   - Avoid mixing with other people, particularly those in a high-risk category, while contagious 
   - Don't return to work early, you could still be contagious
• Antiviral medications that can limit the effect of influenza if they are taken early after onset of symptoms (within the first two days of the illness) are available on prescription.
• Therefore, it is important that you see your GP immediately if you believe that you are suffering influenza and wish to reduce the duration of your illness.

* Based on population data that 105.8 per 100,000 Australians aged under five years are hospitalised due to influenza and the current population figure for that group is 1,371,051 (ABS accessed 5 March 2009).  

If you would like any further information please contact: 

References

1. National Institute of Clinical Studies. Flu Facts. Last viewed: March 2009. Available at: http://www.fightflu.gov.au/asp/index.asp?sid=2118&page=influenza

2. NHMRC. The Australian Immunisation Handbook 9^th Edition 2008. Available at: http://immunise.health.gov.au/internet/immunise/publishing.nsf/Content/Handbook-home

3. Newall AT, Wood JG, MacIntyre CR. Influenza-related hospitalisation and death in Australians aged 50 years and older Vaccine 2008 April; 26(17):2135- 2141

4. World Health Orgnization. Fact Sheet No 211. Revised March 2003. Available at http://www.who.int/mediacentre/factsheets/fs211/en/print.html

5. Newall AT, Scuffham PA, Hodgkinson B. Economic report into the cost of influenza to the Australian health system. 2007 March. Available at: http://www.influenzaspeciailstgroup.org.au/

6. Milne BG, Williams S, May M et al. Influenza A associated morbidity and mortality in a Paediatric Intensive Care Unit. CDI 2004;28(4):504 -508

7. Neuzil KM, Hohlbein C, Zhu Y. Illness Among Schoolchildren During Influenza Season. Arch Pediatr Adolesc Med. 2002;156:986-991

8. Principi N, Esposito S, Gasparini R et al. Burden of influenza in healthy children and their households, Arch Dis Child 2004;89:1002-1007

9. Newell AT, Scuffham PA. Influenza-related disease: The cost to the Australian healthcare system. Vaccine 2008; 26 (52):6818-23

10. Vynnycky E, Pitman R, Siddiqui R et al. Estimating the impact of childhood influenza vaccination programmes in England and Wales. Vaccine 2008;26: 5321-5330

11. Weber T.P., Stilianakis N.I. Inactivation of influenza A viruses in the environment and modes of transmission: A critical review. Journal of Infection (2008) 57, 361-373.

12. Bean B, Moore BM, Sterner B et al. Survival of influenza virus on environmental surfaces. J Infect Dis July 1982;146(1):47-51

13. World Health Organization. Recommended composition of influenza virus vaccines for use in the 2009 southern hemisphere influenza season. 2008. Available at: http://www.who.int/csr/disease/influenza/recommendations2009south/en/index.html

14. Australian Department of Health and Ageing. National Notifiable Diseases Surveillance System. Number of notifications of influenza (laboratory confirmed), Australia, 2006 by age group and sex. Cited 20/02/07. Available at: http://www9.health.gov.au/cda/Source/Rpt_5.cfm