Tuesday, October 13, 2009

Now Hear This !!

This time I'm going to talk about the 'flu. If you don't want to read on - fair enough. If you have some strong views about getting vaccinated (or not), the please read on. You don't have to be convinced, but at least read on with an open mind, and try to follow my arguments (assuming I don't make some horrendous blunder in the middle !). References to what I've said before: see here for a short update on H1N1, and also here for an entry that has references to other sites with more info.

Firstly, some definitions. Influenza is a virus. That means that antibiotics are not any use against it. At all. The body (human or other) defends against viruses by "learning" to recognise the intrinsic "shape" of the virus and then attacking anything with that shape. Something with a very similar shape may be "recognised" in the same way (as being "close enough"), whereas a sufficiently different shape will not trigger the reaction. A vaccine to protect you against a virus has to be able to train your body to react against a new shape. The best way to do this is to introduce your body to the real thing - actually getting infected! However, that's not normally recommended, so we normally use an infection with a virus that has been killed. Even dead, it has the same shape and will teach your body what to react against. Some virus vaccines are alive, but very much weakened: these should really only be taken in emergency or by those not considered at high risk of serious consequences from getting the virus for real.

Talking about risk, you should remember that there are two very different risks here: the risk of contracting the disease and the risk of suffering serious or fatal results when you do contract it. Mathematically, if you have a 1 in 10 chance of getting it, and a 1 in 10 chance of dieing from it, then of the 10 people in 10 that get it, just one can be expected to die. This factoring is often skipped over, both by people trying to calm the masses and also by people trying to inflame fear and uncertainty.

So, to history. About 90 years ago, in 1917, it is believed that there was the beginning of an outbreak of 'flu in China, although this is only a little more than informed speculation and educated guesswork. Little seems to be known of it until later in 1918, when ut started spreading, first in the military and then into the civilian populations in Europe. It is often called Spanish Flu, because many of people contracted it in Spain, where there was also a high death rate amongst the affected. It spread via the trade routes of the world, and affected almost the whole human population, killing millions more than the Great War itself. For reference, see here.

One unusual characteristic of the 1918 'flu was that it's effects were most severely felt in the 15-34 age range, showing a death rate maybe 20 times higher than with previous varieties of the 'flu.

Since the four year of the 1918 Spanish Flu, the strains we have seen have returned to the virulence known before those years. We've had scares about Avian 'Flu, and other things in the last few years, but in 2009 we appear to be back in the cross-hairs again!

About six months ago
a disease that popularly became known as the "Swine Flu" hit Mexico, spread throughout the USA, and has since become pandemic throughout the world. A lot of people died of what is now called "H1N1 influenza", especially in Mexico, but quite a few in the USA and Europe. One characteristic that was noted by an interviewee on an NPR program one Saturday afternoon was that the H1N1 seemed to affect its victims in a way remarkably similar to the symptoms seen in 1918 - that is, the people most severely affected by it are the 15-34 age range! Now, on CNN today, comes an article that repeats this view.

Up until now it has always been considered that a valid explanation for this characteristic of the Spanish Flu was that these groups were preferentially targeted because they were the targets available. This age group was roughly that which was most involved in the previous four years of war. However, that should not explain the similar impact on the population of the USA, which had only experienced about a year of warfare, and of other countries' populations. This was a question that was never properly explained by the idea that it was people weakened by war that were more susceptible, hence the continuing scientific efforts to obtain "infected" DNA from exhumed corpses of the era.

So now for the idea of getting protection against the Thing. Before I start, I should state here that I am on a drug for arthritis (Enbrel) that is an immuno-suppressant, so I have already had a vaccination against the "standard" 'flu this year. Firstly because if I get it then I'll really get it badly, and secondly because if I get 'flu then the doctors won't have to wonder about whether its "standard" 'flu - it won't be. I have no problem in saying that I paid $25 for it at a Walgreen's in NJ, and that it hurt far far less than accidentally pricked with a pin or needle. For more specific info, please see here, which gives a good, concise list of things to think about. Walgreens and CVS, by the way, will give you vaccine without charge if you are unemployed and looking for work. The vaccine for the "standard" 'flu is prepared in exactly the same was as it has been for the last 10 or more years, and has very few risks (the last link describes the risks that do exist).

The H1N1 vaccine is a brand-new vaccine, but created in the same way as the "standard" variety, so will have the same caveats as above. It has been created from intensive research carried out world-wide since last Spring. There are two things to consider here: will it work and will it be available in time. Efficacy is something that only time will tell - we won't know until either nobody with it gets sick or a lot of people do. Availability is another matter. This version of the 'flu is not a seasonal variety, but can be expected to become more severe during the Winter, just like the Spanish Flu did in the four years it ravaged the world.

Some people are worried that the components of the vaccine - aside from the actual vaccine and water there are some preservatives, etc. - can be dangerous. The CDC has reported that some H1N1 shots will contain the preservative Thimerosal, and others won't. Your doctor will know what your shot contains - when I got mine from Walgreens they gave me a pamphlet that explained exactly what was in each type (there were two available), including things like other ingredients. Some people have expressed concern about Thimerosal for children because it's mercury-based, but the CDC states there is no scientific evidence the preservative is harmful.

Other people have expressed (to me) worries that the risks of taking the vaccine are greater than those of not taking it and possibly getting the 'flu. This is a very difficult equation to balance in order to see which way to go. On the one side there is a mathematically describable measurement of how likely you are to get the 'flu, and, if you do, how likely it is to be at any particular severity, from very mild to deadly. On the other side is the same piece of mathematics about the likelihood of being damaged by the vaccine, and the subsequent likelihood of getting the 'flu, and the consequences of that, too! If all that isn't enough, you also have to give mathematical values to how bad you consider degrees of sickness to be! The particular problem with all the above is that there are no numbers for them yet - these won't exist until the 'flu has happened to people, and, by that time, it'll maybe be too late!

So, life is hard. Yes. My personal opinion is that getting 'flu is such a bad experience (I had it when I was 18 and haven't forgotten since!) that I really don't want it again, especially as I don't have an effective immune system any more. So I'm getting the H1N1 jab as soon as I can.

Back soon - stay healthy !

TTFN

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