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Why do the elderly seem to be immune to Swine flu?

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Curtin University of Technology Research Fellow, and internationally renowned zoonotic expert, Professor John MacKenzie claims the elderly seem to be immune to H1N1v virus.

According to Professor MacKenzie it appears as though older people were exposed to a strain of the flu in the 1940s or 1950s causing them to have a residual immunity.

‘This is why elderly people seem to be much more resistant, its probably because  they have residual immunity from an earlier exposure to influenza’ he said.

‘It’s a little bit uncertain but there has to be something of that sort to give them that resistance.’

Saying it is most likely due to something called original antigenic sin, meaning they have had hidden exposure to the very first virus and had an immune response which has resulted in some protection now.

‘It seems the first influenza you are exposed to in life ‘imprints’ itself on your immune system, and whenever you are exposed again, the major immune response is to the first one you encountered, not the new infecting virus – a phenomenon we call original antigenic sin. So, elderly people must have been exposed to a virus in the past which now helps provide some degree of immunity/resistance to the new H1N1v virus.’

Although the immunity seems to have occurred, Professor MacKenzie maintains that until it is known how this new strain will mutate, there is no guarantee of immunity to any mutations of H1N1v if a person has had the virus.

‘It will probably be like a normal flu. Normal flu when you get infected you’re immune probably for the next two seasons.’

‘But on the other hand, depends how much it mutates and don’t forget we’re dealing with a totally novel virus we haven’t seen before and that might mutate faster than normal, we just don’t know.’

If it is as we suspect, it does start mutating as it gets into more and more people, and … we’ll start seeing probably quite large mutations I suspect.’

Professor MacKenzie said the virus is much more dangerous than people are giving it credit for and recommends those with flu-like symptoms should go into self-imposed quarantine in order to contain the virus from spreading through the general population.

He said those trying to get the H1N1v in order to become immune are not necessarily, although it is a possibility, increasing the chances of it mutating but are putting themselves at dire risk.

‘There’s no point these people going to parties and catching it because they are putting themselves in the firing line.’

‘I think the major issue in terms of flu parties is people who maybe much more vulnerable than they realise and they’re putting themselves at risk.’

Professor MacKenzie said those who are contracting the virus are usually those that least expect to get sick because it is affecting normally healthy people, however those with chronic conditions are at a higher risk.

‘Most of the serious cases we’ve had, most hospitalisations anyhow, have been in school children and in young adults … very healthy people.’

‘The high risks groups, currently, are young adults who are very much overweight, or who have chronic diseases like diabetes, or asthma, or who have chronic broncho-pulmonary disease of some sort, and so these people really are very much at risk compared to the rest of the population. So you really don’t want to catch it.’

‘Morbid obesity has been shown to be a risk factor in serious cases of H1N1v infection in North America.’

Professor MacKenzie said chronic broncho-pulmonary diseases (lung and circulatory): ‘have always been risk factors for influenza because of where the virus replicates and causes tissue damage, and other chronic diseases such as diabetes or asthma can affect the ability to mount resistance through immune response etcetera and also because they affect the lungs and respiratory system’.

Although it is still unknown whether it will become worse when the virus mutates Professor MacKenzie said immunity can not be definite until it is known how the virus behaves after it has mutated and maintained that people should remain wary.

‘I think that the most important message we have at present is that this virus, it might seem like seasonal flu but it’s not, it’s much more serious.’

According to Professor MacKenzie an influenza pandemic has been expected for the past two to three decades with the last occurring in 1968.

‘In the past there have been influenza pandemics every 10-40 years.’

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