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Asked by alysha to Hitesh, Hywel, Mae, Nik, Tiffany on 13 Jun 2012.
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Tiffany Taylor answered on 13 Jun 2012:
The reason the flu virus is a bit different each year is because the virus is evolving. You can only be infected by the same type of virus once, because your immune system will recognise it from then on, and wipe it out before it can make you sick. The way diseases get around this is by evolving so the immune system doesn’t recognised it any more. So what the scientists do is look at which strains of flu are best at avoiding detection by the immune system, and concentrate on developing vaccines for those. It’s a race to keep up with the disease!
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Nicola Ibberson answered on 14 Jun 2012:
The simple answer is that they don’t know! They have no idea how the virus will evolve from year to year, and which ‘strains’ of the bacteria are going to be the big problem, but they can make an educated guess based on how the virus has behaved in the past and which viral strains seem to be ‘up and coming’. To improve their chances of getting it right, they actually vaccinate against three different viral strains every year (given by a single injection). But there is always a chance that they could get it wrong!
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Mae Woods answered on 15 Jun 2012:
They make a new one every time there is a new virus. They start making them in places like the National Institute for Biological Standards and then ship them to high production places once they are happy with the vaccination.
They can be made by producing lots of the virus in an egg. Once lots of the new and harmful virus has been made in the egg, it is mixed with another old virus to trick the body into thinking it has the harmful virus when in fact the two mixed together are harmless.
Because the body thinks it has the virus it begins to make cells that can fight it which is good because then the body is ready to fight the real thing
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