• Question: How do scientists know how to make a flu vaccine if viruses can be different every year?

    Asked by benjb018 to Ben, Jony, Katharine, Mark on 23 Nov 2011.
    • Photo: Ben Still

      Ben Still answered on 23 Nov 2011:

      There are certain commonalities amongst viruses and it is these commonalities that are used to produce a vaccine – they may not be 100% effective but they do improve the immunity to the general feature of a virus – kind of like training in a virtual world for real world activities, there are always subtle differences.

    • Photo: Mark Basham

      Mark Basham answered on 23 Nov 2011:

      So the thing is is knowing how vaccines work. All they do is let your immune system fight a weaker version of an illness (by making you contract that harmless illness), the idea being that your immune system then remembers how to fight that type of virus. When you get a real virus (Which may well be really nasty), its then exactly as Ben said, your immune system has had some training in how to fight that type of virus, and so preforms better, and you get better sooner, or not at all if your immune system can deal with it quickly enough.

      The clever bit is that its all your own amazingly powerful Immune System which is keeping you healthy, the vaccines are just giving it some practice in a safe enviroment.

    • Photo: Jony Hudson

      Jony Hudson answered on 23 Nov 2011:

      To add to what the guys above said. They also try to predict exactly what strains of flu are going to appear each year, by tracking early cases. They then target the vaccine to give immunity to the ones that are most likely to come up.

      It doesn’t always work, because sometimes a new strain appears and spreads rapidly, or the predictions just don’t work out because of bad luck. But it’s usually pretty good.

      This is why you can’t get flu vaccine each year until the middle of September. It’s because they’re waiting to see what strains are going to be the important ones that winter.

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