Surge testing as begun across the UK in a race against the spread of the new Covid Indian variant.
The drive in tests will be carried out in Bedford, Burnley, Hounslow, Kirklees, Leicester and North Tyneside after a rapid rise in cases of the new variant - feared to be up to 50% more transmissible.
Almost 3,000 cases of the Indian variant have now been identified in the UK - up from the 2,323 declared on Monday.
The latest figures mean cases in the UK are up 8.6% week on week, with deaths up 10.4%.
In a press conference yesterday, Health Secretary Matt Hancock said areas where surge testing has been deployed were selected via "an incredibly sensitive biosecurity surveillance system" - which spotted cases in earlier variant hotspots Bolton and Blackburn.
It included monitoring travel patterns, along with analysing wastewater to help identify where variants were and where they were at risk of spreading to, he said.
Hancock added: "The weekly case data in Bolton is now 283 per 100,000 and it doubled in the last week.
"There are now 25 people in Bolton Hospital with Covid - the majority are unvaccinated, nearly 90% have not yet had two vaccines.
"This shows the importance of getting vaccinated, not once but twice."
Overall, a further three deaths within 28 days of a positive test have been recorded and there have been 2,696 more cases overall.
Prof Van-Tam told a Downing Street press conference on Wednesday: "I pitch this personally as a straight race between the transmissibility of this new variant ... and vaccine delivery.
"The NHS is doing everything it can to turbo-boost that, and that is the challenge that's ahead of us in the next two to three to four weeks, to make sure that we outrun the virus through really vigorous pull-through on vaccine delivery."
Prof Van-Tam said scientists would have more information by next week on how transmissible the Indian variant is versus the Kent strain, which has become dominant in the UK.
Experts had feared it could be up to 50% more transmissible, but the Government adviser suggested studies could find it is only half that.
Prof Van-Tam added: "We have a credible range that goes from a few per cent more transmissible through to 50% more transmissible - I think most people feel it is going to be somewhere in the middle... but it is just too early."
