Jonathan Van-Tam has warned of “sobering” coronavirus numbers as the latest figures revealed infections are rising in one in five UK areas.
Prof Van-Tam, England’s deputy chief medical officer, warned: “This is not a good sign.”
It follows the optimism surrounding Boris Johnson’s “road map” out of England’s lockdown and the continued rollout of the vaccine.
However, the government’s latest infection figures, for the seven days up to 21 February, show rising case rates in 95 local council areas.
This interactive map shows whether cases are rising or falling in your area. A list of 15 areas with the highest increases can also be seen at the bottom of this page.
Prof Van-Tam said at Friday’s Downing Street press conference: “In some parts of the UK, case rates are changing, albeit slowly, but in the wrong direction.
“This is not a good sign and reinforces the fact that I’m afraid this battle at the moment is not won.”
Health secretary Matt Hancock said the figures are "stark" as he also warned: "We're not there yet."
Watch: Matt Hancock warns public 'this isn't over yet'
"The number of cases is now falling by only 15% a week," Hancock said. "In some areas of the country, that has flattened entirely and one in five local authority areas has seen a rise in cases in the last week.
"I just want to say this about the figures. This stark picture shows that this isn’t over yet. The ‘stay at home’ rules are still in place for a reason."
Amid the news this week about the 21 June target date for lockdown to end in England, as well as 19,177,555 people having been given a first dose of the vaccine as of Thursday, Prof Van-Tam also warned that failing to follow restrictions now could lead to the lockdown "road map" being delayed.
“I do worry that people think it’s all over," he said.
“The more they think that when it’s not, the greater the headwind they’re going to give to the vaccine programme and the more at risk will become the milestones set on the road map."
Hancock, meanwhile, did not rule out enforcing separate restrictions locally: “We proposed to come out of the national lockdown all together. These regional disparities are smaller than we saw in the autumn.
“We don’t rule out taking local action in an individual area as we see a spike. But the goal is for us all to come out together.”
The 15 areas with the highest increases in seven-day case rates per 100,000 people
East Lothian: 81.20%
Mid and East Antrim: 80.40%
East Dunbartonshire: 70.00%
City of Edinburgh: 55.50%
Dundee City: 54.70%
North Warwickshire: 30.80%
Lisburn and Castlereagh: 29.90%
Merthyr Tydfil: 28.60%
Malvern Hills: 27.40%
Watch: How England will leave lockdown