Data from hospitals in areas ravaged by the Indian variant of Covid will reportedly reveal if lockdown easing could be de-railed as early as next week.
Sewage is also said to now be under surveillance in a bid to find early warning signs of variant outbreaks in other parts of the country.
Boris Johnson said on Tuesday the government will know more "in a few days" whether the Covid roadmap can go ahead as planned.
On Monday a raft of lockdown restrictions were lifted in England as part of the roadmap out of lockdown. The Prime Minister said there was "nothing conclusive" to suggest he should deviate from the plans to relax even more restrictions from June 21.