England may face tougher tiered restrictions to help stop the spread of coronavirus when the national lockdown ends, a government adviser has revealed.
Dr Susan Hopkins suggested that regional rules around social mixing and which businesses must close could be "strengthened" in some areas to help keep COVID-19 cases low.
The epidemiologist and interim chief medical officer of Test and Trace revealed concerns around the limited effects of Tiers 1 and 2 - the lowest and medium threat levels.
Attention has already turned to what will replace the national lockdown, due to end on 2 December, particularly as families contemplate how they can celebrate Christmas during a pandemic.
Another 21,363 infections and 213 deaths were reported across the UK on Monday.
Speaking at a Downing Street briefing, Dr Hopkins said Tier 3 - the highest level, which areas like Greater Manchester, Lancashire and South Yorkshire were living under - had "had an effect" in reducing cases.
But of Tier 2, which London was in, she said it "seems to hold in some areas and not so well in others" - and that this depended on how quickly coronavirus was spreading and on the level of people's compliance.
But on Tier 1, Dr Hopkins was blunt - saying: "We see very little effect."
Overall, she predicted all tiers could be toughened to keep coronavirus suppressed as the country heads into winter.
"When we look at what tiers may be there in the future, we will have to think about strengthening them in order to get us through the winter months until the vaccine is available for everyone," Dr Hopkins said.
Health Secretary Matt Hancock said he "hoped" the national lockdown would be replaced with a tiered system "similar to what we had before".
But he cautioned that it was too early to tell how effective the lockdown had been, after announcing five million vaccine doses had been ordered from Moderna - which could have a 94.5% effectiveness.
"At the moment," the minister said, "most of the tests we're getting back, and most of the positive cases, are from around the time the lockdown came in, so we are yet to see in the data.
"It's too early to expect to see in the data - the impact of the second lockdown."
More concrete information on what restrictions will replace the lockdown are expected to be set out next week, Boris Johnson's spokesman said on Monday.
He told reporters: "We are committed to setting out next week what the replacement regime will be and that will be a return to the localised approach, and we're actively working on those plans at the moment."
The prime minister likely would have done so in-person, but he is self-isolating for two weeks after a Tory MP who he met with in Downing Street tested positive for COVID-19.
In Scotland, First Minister Nicola Sturgeon has set up a five-level system of coronavirus restrictions.
