Boris Johnson said there is currently no "conclusive" evidence to deviate from the road map out of lockdown despite concerns over the Indian coronavirus variant.
The Prime Minister has previously warned the rise in cases of the highly transmissible variant of concern could risk the next stage of England's road map out of lockdown, currently pencilled in for June 21, being delayed.
If outbreaks are limited, ministers could opt instead to push ahead with the reopening while keeping some areas under restrictions in an echo of the controversial tiers system introduced in 2020.
The Prime Minister said the "wall of defences" built up by the vaccination programme meant "I don't see anything conclusive at the moment to say that we need to deviate from the road map".
But, he added: "We've got to be cautious and we are keeping everything under very close observation.
"We'll know a lot more in a few days' time."
Mr Johnson said data from hotspots including Bolton, Blackburn, Bedford and Sefton were being examined to find out more about the impact of the variant.
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Asked whether local lockdowns could be used, Mr Johnson said: "We've just got to be cautious about the way we approach it and we will be letting people know as much as we can, as soon as we can.
"But at the moment we don't see anything conclusive that makes us think we have to deviate from the road map."
Earlier, Cabinet minister George Eustice had said local lockdowns "would be an option and we cannot rule anything out".
Environment Secretary Mr Eustice told Sky News efforts were being stepped up to increase vaccine uptake, particularly among minority groups.
He said that in "pockets where uptake is low" efforts were being made with "community leaders, faith leaders in some of those BAME (black and minority ethnic) communities to really encourage people to come forward and have the vaccine".
On LBC Radio he suggested that younger people needed to show the same enthusiasm for the jabs as the over-60s.
He said: "We just need all those other, younger cohorts to also embrace the vaccine."