BBCNEWS BBC News December 27, 2021 13:25:00
Some parts of the world, a particular variant has had very little impact, whereas in others it has had a devastating impact. do we have any idea why that is? there are lots of factors going on. partly it is the population — how old is the population, do they have chronic conditions, what proportion have been vaccinated, have they been infected before? all these things will have an impact on the impact of the vaccine — what other measures are being taken, how much is the population mixing with each other? to some extent, if we know all these we can try to work out what might be happening. b...