The coronavirus will not be eliminated and people will have to learn to live with it, Tony Blair has warned.
The former Labour PM said the UK required more “containment infrastructure” in case the virus resurges in the autumn.
His think-tank has recommended widespread mask-wearing to prevent a spike in cases as lockdown is eased.
Boris Johnson said the UK will be “well on the way past” the pandemic by the middle of next year.
But the prime minister told reporters there would still be “tough times ahead in keeping this virus under control”.
Speaking to the Press Association, Mr Blair – prime minister from 1997 to 2007 – said it was “absolutely essential” to prepare for a “50/50 chance” the disease would resurge in the autumn.
He said that action needed to be taken now to make sure the virus could be contained in the long-term, with a return to nationwide lockdown not possible.
“The reality is that we’re going to be living with Covid-19 – we’re not really going to be able to eliminate it,” he said.
“My anxiety about the government at the moment is that it has still not really put in place that infrastructure of containment that is going to see us through a resurgence of the disease if unfortunately that happens.”
On Friday, Mr Johnson said the planet had “faced a very nasty new foe in the form of a bug that we didn’t know about before”.
He added: “I think that by the middle of next year…we will be well on the way past it.
“But … I must be clear with people, I do still think that we have tough times ahead in keeping this virus under control.”
In a report, the Tony Blair Institute for Global Change argued scoring people A-D on their vulnerability would allow them to “take ownership of their own risk”.
It recommended people should be ordered to wear face masks in “all public environments”.
Key workers such as teachers, healthcare workers, and those who work on public transport should be supplied with plastic face shields, it argued.
And it said those most risk from the virus should be offered government-issued N95 medical masks in a special colour, as a “visual sign” they are shielding.
Face coverings are now compulsory for customers in shops in England, and have been in Scotland since 10 July. Shoppers are not currently required to wear them in Wales or Northern Ireland.
Coverings are already compulsory on public transport in England and Scotland, as well as most buses, trains and ferries in Northern Ireland.
They will be mandatory on public transport in Wales from 27 July.
Increased testing target
Health leaders have called for a cross-party review of preparations for a possible resurgence of the virus later this year.
Questioned about the recommendation earlier this month, Boris Johnson vowed to do “absolutely everything in our power to prevent a second spike”.
The government has set a target of being able to process 500,000 tests per day by the end of October through an expanded network of walk-in centres.
Increased winter funding for the NHS in England has also been pledged, along with expanded eligibly for free flu vaccination ahead of the winter.