The roadmap for easing coronavirus restrictions will involve four tests that have to be met before any unlocking can begin.
The government will use the metrics in England to assess the impact of loosening the rules at each stage.
If any of the conditions are not met, the pace of the unlocking could be slowed.
With the UK having suffered the world's fifth-highest official death toll and its biggest economic crash in more than 300 years, the prime minister is expected to proceed with more caution this time around, having said he wants the current lockdown to be the last.
The four tests are:
The vaccine deployment programme continues successfully
Evidence shows vaccines are sufficiently effective in reducing hospitalisations and deaths in those vaccinated
Infection rates do not risk a surge in hospitalisations which would put unsustainable pressure on the NHS
The assessment of the risks is not fundamentally changed by new variants of the virus
There is likely to be a five-week gap between each stage of the unlocking to allow time for the changes to take effect and to ensure that the four conditions are met each time before further easing is allowed to happen.
More than a quarter of the population – some 17.6 million people – have now received a first dose, behind only Israel and the United Arab Emirates in vaccines per head of population.
The government aims to give a first dose to all adults by the end of July.