The president of South Africa has criticised travel restrictions imposed after the emergence of the Omicron variant, and questioned the justification for them.

Cyril Ramaphosa said: "The prohibition of travel is not informed by science, nor will it be effective in preventing the spread of this variant."

Various countries have restricted or banned travel from southern Africa, and the UK has now added Nigeria to its list of African countries from which travel is restricted.

So what does the science say?

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