An infectious diseases expert has warned England could be forced to implement snap lockdowns to deal with surges in COVID-19 cases.
Professor Greg Towers, from the Division of Infection and Immunity at University College London, said if people treated the virus like "it's all over" it would trigger high infection rates.
“If we don’t wear masks, and if we ignore social distancing rules, and if we just pretend it’s all over, then what’s going to happen is we’ll get another big wave of infection, and we’ll get put into lockdown again - so, if we don’t want lockdown, we’ve got to try and stop the spread by easier means like mask-wearing and social distancing," he told Times Radio.
The warning comes with the UK is set to announce an expansion of the COVID booster vaccine programme after nine cases of the Omicron variant have been confirmed across the country.
Watch: No Plan B for England yet, says minister
From Tuesday, the wearing of face masks is set to be compulsory in shops and on public transport, while PCR tests will be brought back in for travellers returning to the UK.
However, ministers have consistently said the prospect of returning to lockdown is not on the table.
Prof Towers added: “We’re looking at behaving in such a way that we suppress waves of infection when they’re on their way – and that I hope will be through vaccination."
He expressed optimism about adapting current vaccines to tackle the emergence of new variants.
“Even if this virus is good at escaping the first vaccine, the vaccine can be modified to make one that is more specific to these new variants," he said.
“And so there are answers to all this, but we just have to keep managing it.
"We have to not say: ‘When is this going to be over?’ We just have to learn to say: ‘I’m going to wear a mask today on the Tube, because that will protect my fellow passengers and reduce the chance of us going into lockdown again’.”
Scientists have warned that the high number of mutations could enable the variant to have some level of resistance to vaccines and appears to be more transmissible, although the World Health Organization has said it will take a few weeks to gather real-world data to confirm this.
Cases have been detected across the world, including in the UK, Israel, South Africa, and Hong Kong triggering border closures; the UK has banned travel from South Africa, with Israel closing its borders all together.
In a statement last week, the WHO said: "This variant has a large number of mutations, some of which are concerning."
At a Downing Street press conference on Saturday, Boris Johnson announced that measures - such as compulsory mask wearing - would return in light of the discovery of the new variant, as well as mandatory PCR tests for all international arrivals.
Johnson stopped short of implementing "Plan B", which would include things like encouraging employers to get employees to work from home, and continued to encourage the public to get their booster vaccines.
Scientists have expressed concern that without global, widespread vaccination new strains like Omicron could become common place.
Dr Peter Droba, an academic at Oxford University who specialises in infectious diseases, warned failing to help low income countries vaccinate their citizens risks them becoming a "breeding ground" for variants.
“The conditions where you have low levels of vaccination and high levels (of virus) circulating are the perfect breeding ground for variants which are resistant to vaccines," he said.
“So, by allowing this continued moral failure of not being more creative and ambitious and aggressive in vaccinating everyone around the world, we have made it more likely for things like the Omicron variant to appear.”
Watch: What do we know about the Omicron variant?