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GP diary: beware Tamiflu panic
Updated on 14 August 2009
By Channel 4 News
Dr Peter Stott, writing for Channel 4 News from his surgery in Surrey, explains why irresponsible Tamiflu use could boost the spread of swine flu.
I was chatting about swine flu to one of my patients today and we got on to the subject of Tamiflu.
"I've already got some," she said. "I rang the flu advice line and pretended to have symptoms. They gave me a number to get some from the chemist.
"I wanted to take some with me on holiday just in case."
I told her that I thought this was the height of irresponsibility and that I was surprised that one of my apparently sensible patients should have behaved in this way.
Tamiflu works by stopping the virus multiplying in the body and it does this in a very clever way.
Viruses are effectively parasites which use mechanisms inside human or animal cells to replicate.
The new viruses buds off from the surface of the infected cell and is released to infect others.
This process requires a chemical called neuraminidase and Tamiflu blocks the action of this chemical.
So the virus cannot escape and stays inside the first cell. Tamiflu has to be taken early in the infection before too many cells have been affected.
After this time, the host's natural immune mechanisms like interferon will kick in and give protection.
In clinical trials Tamiflu reduces the duration of symptoms by approximately one day - a benefit that many consider may not be worth the cost and effort for patients who have only a mild illness.
The flu virus however is very clever and very quickly develops ways to become resistant to antivirals.
It is rather like trying to find your way to your favourite restaurant in a city centre. Even if they close one road, there are always other routes. It may take a little time to find it, but you will do eventually.
Similarly, there are lots of types of neuraminidases - lots of ways for the virus to get out of the cell and eventually the flu virus will mutate and be able to produce one.
We categorise neuraminidases as N1, N2, N3 etc but there are also sub-types. Swine flu is one of the H1N1viruses which are usually the nasty ones.
Tamiflu has been used for several winters now, given to patients with normal H1N1 winter strains and we are already beginning to see signs of resistance.
In the fourth quarter of 2008, the World Health Organisation reported that of that winter?s circulating influenza A (H1N1) flu virus, 95 per cent were resistant. We have only seen one resistant case of swine flu this year, in Denmark.
Happily this has not spread, but the fear of scientists is that swine flu will combine with one of these resistant strains, a change which would render Tamiflu ineffective.
So back to my patient. Why was I so upset?
First using Tamiflu for mild cases in fit people is probably not necessary. Second, widespread use will lead to increased resistance because the virus will get used to Tamiflu and it may be ineffective when we might really need it ? if the virus mutates to become more pathogenic.
Last, it's costing a lot of money for only minimal benefit. We have stockpiled 33m doses of Tamiflu which at normal pharmacy prices is worth over half a billion pounds - money that could be better spent on lots of other things.
There is a direct corollary between antivirals and antibiotics. Everyone understands that antibiotics have to be used responsibly. Otherwise resistance will develop and they will become ineffective. This will inevitably happen for antivirals too.
The government and the Department of Health have made antivirals very easily available through this flu epidemic, much more easily available than antibiotics have ever been.
You can get them immediately, on the phone, online and without a doctor's prescription. Be assured they will be there if you need them.
It is everyone's duty to use these medicines responsibly in the correct people, in the correct circumstance and for the correct illness.
Not to do so will only encourage viral resistance and could as a result, put the whole population at increased risk.
Dr Peter Stott is a GP at the Tadworth Medical Centre in Surrey.
<!--googleoff: index-->http://www.channel4.com/news/article...+panic/3308757
Updated on 14 August 2009
By Channel 4 News
Dr Peter Stott, writing for Channel 4 News from his surgery in Surrey, explains why irresponsible Tamiflu use could boost the spread of swine flu.
I was chatting about swine flu to one of my patients today and we got on to the subject of Tamiflu.
"I've already got some," she said. "I rang the flu advice line and pretended to have symptoms. They gave me a number to get some from the chemist.
"I wanted to take some with me on holiday just in case."
I told her that I thought this was the height of irresponsibility and that I was surprised that one of my apparently sensible patients should have behaved in this way.
Tamiflu works by stopping the virus multiplying in the body and it does this in a very clever way.
Viruses are effectively parasites which use mechanisms inside human or animal cells to replicate.
The new viruses buds off from the surface of the infected cell and is released to infect others.
This process requires a chemical called neuraminidase and Tamiflu blocks the action of this chemical.
So the virus cannot escape and stays inside the first cell. Tamiflu has to be taken early in the infection before too many cells have been affected.
After this time, the host's natural immune mechanisms like interferon will kick in and give protection.
In clinical trials Tamiflu reduces the duration of symptoms by approximately one day - a benefit that many consider may not be worth the cost and effort for patients who have only a mild illness.
The flu virus however is very clever and very quickly develops ways to become resistant to antivirals.
It is rather like trying to find your way to your favourite restaurant in a city centre. Even if they close one road, there are always other routes. It may take a little time to find it, but you will do eventually.
Similarly, there are lots of types of neuraminidases - lots of ways for the virus to get out of the cell and eventually the flu virus will mutate and be able to produce one.
We categorise neuraminidases as N1, N2, N3 etc but there are also sub-types. Swine flu is one of the H1N1viruses which are usually the nasty ones.
Tamiflu has been used for several winters now, given to patients with normal H1N1 winter strains and we are already beginning to see signs of resistance.
In the fourth quarter of 2008, the World Health Organisation reported that of that winter?s circulating influenza A (H1N1) flu virus, 95 per cent were resistant. We have only seen one resistant case of swine flu this year, in Denmark.
Happily this has not spread, but the fear of scientists is that swine flu will combine with one of these resistant strains, a change which would render Tamiflu ineffective.
So back to my patient. Why was I so upset?
First using Tamiflu for mild cases in fit people is probably not necessary. Second, widespread use will lead to increased resistance because the virus will get used to Tamiflu and it may be ineffective when we might really need it ? if the virus mutates to become more pathogenic.
Last, it's costing a lot of money for only minimal benefit. We have stockpiled 33m doses of Tamiflu which at normal pharmacy prices is worth over half a billion pounds - money that could be better spent on lots of other things.
There is a direct corollary between antivirals and antibiotics. Everyone understands that antibiotics have to be used responsibly. Otherwise resistance will develop and they will become ineffective. This will inevitably happen for antivirals too.
The government and the Department of Health have made antivirals very easily available through this flu epidemic, much more easily available than antibiotics have ever been.
You can get them immediately, on the phone, online and without a doctor's prescription. Be assured they will be there if you need them.
It is everyone's duty to use these medicines responsibly in the correct people, in the correct circumstance and for the correct illness.
Not to do so will only encourage viral resistance and could as a result, put the whole population at increased risk.
Dr Peter Stott is a GP at the Tadworth Medical Centre in Surrey.<!--googleoff: index-->http://www.channel4.com/news/article...+panic/3308757
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