The new Omicron variant could lead to more deaths due to its infectiousness and ability to re-infect people who have already had Covid, said an expert.
Scientists are currently unsure how seriously ill people will get when they catch the new variant of Covid.
Some experts believe infection with the Omicron variant may be much milder for most people.
However, not only does Omicron appear to spread more quickly and easily than the Delta variant, it also seems to evade protection from vaccines and previous Covid infections.
Researcher Professor Tim Spector, co-founder of the ZOE Covid Study app, says even if fewer people get seriously ill, that could still be a huge problem.
The ZOE Covid Study is a partnership between King's College London and the health science company ZOE which conducts non-profit Covid research.
Asked whether Omicron could infect more people but make fewer people sick, Prof Spector, told BBC Breakfast: "If early reports pan out – we don’t absolutely know this, we've got hardly any data in this country where we have high rates of vaccination – but if we assume that it is not more severe and possibly milder than Delta, but it’s much more transmissible…
"So it means that perhaps twice as many people are going to pass it on from when someone gets it in a crowd.
"But it's also means that eventually you will get more deaths and problems, because nearly everyone is infected or re-infected.
"And so, this this means that for the country as a whole, it could be worse news but better for the individual. So it’s absolutely no reason for complacency."
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