Influenza – Backgrounder 2006 92.41 Kb

What is influenza?

•  Influenza is a debilitating illness whose affects are felt throughout the whole body, with symptoms including fever, headaches, muscle aches and pains.

•  Even healthy young adults may take several weeks to recover from influenza, and for some people it can lead to hospitalisation or even death.
•  Many people confuse the common cold with influenza. However, colds are much less serious with different symptoms and less potential for severe or life-threatening illness.
• How easily is it transmitted?
•  Influenza is a virus which is spread when infected people cough or sneeze into the air, transmitting droplets which are breathed in by other people.
  • One cough or sneeze can transmit the virus up to two metres
  • It is estimated that a person who has influenza could pass it on to up to a dozen other people
•  The infection can also be acquired by contact by hand to face (mouth, eye) contact with contaminated surfaces.

How contagious is influenza?

•  Influenza is highly contagious. After someone coughs or sneezes the virus can survive for:
  • Up to an hour in the air in enclosed environments¹
  • More than eight hours on hard surfaces such as stainless steel and plastic²
  • Up to five minutes on hands after transfer from other surfaces²

Who is at particular risk of complications from influenza?

•  People at particular risk of severe complications from influenza are those with heart conditions, asthma and other lung conditions, diabetes, kidney problems, those with weakened immune systems, residents of nursing homes and other long-term care facilities, as well as anybody aged 65 and over regardless of their health status³
  • Australia has had great success in vaccinating people 65 years and over, with around 80% of this age group getting vaccinated, whereas only 42% of people <65 with at-risk conditions receive the annual influenza vaccination⁴
  • Studies in the USA and UK have shown that up to a quarter^5,6 of all people who die from influenza are under 65 years of age
•  In addition, it is important that people who care for - or are in close contact with - people who are at particular risk, also avoid infection to avert passing it on to them.
•  Many otherwise healthy Australians can't afford to get influenza, such as those who are selfemployed, single parents, carers or people who can't afford to take any time off work. Falling victim to influenza could mean that important life events and activities are missed, resulting in unnecessary suffering as well as economic hardship for many Australians.

How does it affect Australians?

•  In the last century more people died from annual seasonal influenza than in the three influenza pandemics⁷.and twice as many Australians die of influenza and pneumonia than in traffic accidents.⁸
•  An Australian study from the early 1990s estimated that influenza was annually responsible for:⁹
  • 1 million medical consultations
  • 20,000-40,000 hospitalisations
  • 1.5 million days off work
  • A total economic cost of about $600 million - a cost which could be expected to have increased since
•  Recent research has shown that the cost of influenza infection on those with at-risk conditions under 65 years of age amounts to $130m per year in Australia¹⁰
•  In Australia, significant levels of influenza occur most years with more severe outbreaks every 2-3 years
•  Influenza pandemics have occurred at irregular and unpredictable intervals. The world experienced three pandemics last century¹¹

Estimated Deaths

1918-19 (Spanish) 21-50 million

1957 (Asian) 1-2 million

1968-69 (Hong Kong) 1 million

How can you reduce your risk of catching influenza?

• A new vaccine is formulated every year to ensure that Australians are given the best possible protection - the vaccine protects people against three strains of influenza which the World Health
• Organization identifies as the most likely to cause outbreaks for that season.
•  The 2006 Southern Hemisphere influenza vaccine includes the following influenza strains:

-          A/New Caledonia

-          A/New York

-          B/Malaysia

•  No vaccine is 100% effective; however influenza vaccination is very effective in protecting against the severe consequences of infection. Studies have convincingly shown it greatly reduces the cases of pneumonia, hospitalisation due to respiratory illness and the total deaths occurring during an influenza season.12
•  For most parts of Australia influenza vaccination is best carried out in the autumn, before serious outbreaks can begin to occur. The majority of people will become infected between July-September.
• You should visit your GP now, before the winter season starts, to get vaccinated against influenza.
•  In the far north of Australia influenza outbreaks can occur early in the year and vaccination should be practiced as early as possible.
•  Many people who should be vaccinated are not, because they believe being fit and healthy will protect them against influenza. This is not the case. 

What can you do if you catch influenza?

• There are specific antiviral medications available on prescription which can help limit the effect of influenza if they are taken early after the onset of symptoms (within the first two days of the illness).
•  If you think you are getting influenza and wish to reduce the time and severity of your illness it's important that you see your GP immediately.
•  The availability of treatments does not lessen the need for people to still get vaccinated - it is important that all those in risk-groups, as well as others who can't afford to get influenza, get vaccinated every year as their first line of defence.
• Avian influenza update:
•  The first human cases of the current H5N1 strain of bird flu, or avian influenza, were reported from Vietnam in December 2003.
•  To date there have been a total of 105 confirmed deaths from avian influenza worldwide, with a majority of cases being reported from South East Asia and China.
•  Wild birds infected with the H5N1 strain of avian influenza have been confirmed in many European countries since October 2005 but no human infections have been reported.
•  In addition to humans, other mammals to have confirmed cases of H5N1 include domestic cats, stone martens, pigs, and tigers.
•  All evidence to date indicates that close contact with dead or sick birds is the principle source of human infection with the H5N1 virus. Furthermore, most human cases have been traced back to contact with sick poultry. However, it is believed that avian influenza could acquire the ability to easily pass from person to person and therefore poses a potential pandemic threat.
•  While avian influenza has not yet appeared in Australia it is important that we remain vigilant,
• particularly due to our close proximity to Asia.

References:

1. Knight V. Viruses as agents of airborne contagion [chapter V]. Annals of the New York Academic Sciences 1980;353:147-156

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

3. NHMRC. The Australian Immunisation Handbook 8 th Edition: 2003 (http://www9.health.gov.au/immhandbook/ ). Last reviewed: March 2006

4. Australian Institute of Health and Welfare. 2004 Adult vaccination survey http://www.aihw.gov.au/publications/phe/avssr04/avssr04.pdf

5. Alling DW, Blackwelder WC, Stuart Harris CH. 1981. A study of excess mortality during influenza epidemics in the United States, 1968-1976. Am.J.Epidemiol. 113 :30-43

6. Tillett HE, Smith JW, Gooch CD. 1983. Excess deaths attributable to influenza in England and Wales: age at death and certified cause. Int.J.Epidemiol. 12:344-352

7. Wilschut J. & McElhaney J.E. Influenza. Elsevier Limited. Spain. 2005. p. 15.

8. Australian Bureau of Statistics. Causes of death Australia 2003: 3303.0 p38-39

9. Mills, J. and Yapp, T. An economic evaluation of three CSIRO manufacturing research projects. 1996. Australia, CSIRO

10. Colgan, S., Kiusiang, TT., Shih, Sophy, Carter, R., Influenza vaccination for ‘at risk' Australian adults aged between 18 to 64. 2006. NICS Evidence Report.

www.fightflu.com.au

11. De Ravin JW, Gerrard PN. The effect of influenza on Australian mortality. Annual Transactions of the Australian Institute of Actuaries 1984; 471-479

12. Vu T et al. A meta-analysis of effectiveness of influenza vaccine in persons aged 65 years and over living in the community. Vaccine 2002; 20: 1831-1836.

Content Updated ( Tuesday, 04 April 2006 )