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I also wonder how they are going to produce enough of it within the time period, the UK has ordered 40 million units, the US is 6x bigger so that's potentially another 250 million, then there's all the other countries the world population topped 7.8 Billion earlier in the year.
For things like the flu jabs, the virus has to be incubated in hens eggs as part of the production process, which is why the WHO has to predict which strains will be important in the following winter in about January, to allow enough time.
I'm told by a friend who knows these things (an ex-microbiologist) that the Pfizer vaccine is based on mRNA, and can use a much, much faster production method.
So yes, still huge amounts of production needed, but it's not such a problem as it might have been had the flu-type method been required.