The London NHS Nightingale hospital is to go "on standby" because no new coronavirus admissions are expected, Downing Street has said.
The temporary hospital was opened on 3 April at London's ExCel exhibition centre and is able to hold 4,000 patients.
Built in nine days, it is one of a number set up to help treat the sickest COVID-19 patients transferred from other hospitals.
However, the number of people with the virus in London hospitals has more than halved in the last month to about 2,000.
The prime minister's spokesman said: "It's not likely that in the coming days we will need to be admitting patients to the London Nightingale while coronavirus in the capital remains under control.
"That's obviously a very positive thing and we remain grateful to everybody in London for following the government's advice in helping to protect the NHS.
"What the Nightingale will be is effectively placed on standby so it would be ready to receive patients should that be required, but we are not anticipating that will be the case."
The spokesman said the Nightingale hospitals around the UK were "absolutely not" a waste of money.
He said the fact they had so far not been used in a "significant way" was "something positive" and showed the NHS had not been overwhelmed.
The Nightingale's chief executive, Professor Charles Knight, told staff it would "stand ready" should cases climb again.
"As a result, after the last of this our first group of patients leaves, the hospital will be placed on standby, ready to resume operations as and when needed in the weeks and potentially months to come," he said.
The number of patients being treated at each of the country's Nightingale hospitals is unclear - but demand appears to have fallen well short of worst-case scenarios.
The PM's spokesman said: "Manchester has taken some patients already; Birmingham, Harrogate and Bristol are ready to take patients if needed.
"The other two are Sunderland and Exeter and they are due to open shortly."
NHS staff, contractors and about 200 military personnel helped construct the London Nightingale, with the first patients admitted on 7 April.
It is estimated that more than 16,000 members of staff would be needed to run it should it ever reach full capacity.
Everything you’ve ever wanted is on the other side of fear.