Some of the 4,000 beds in the new NHS Nightingale hospital have been taken up by Covid-19 patients.
The first patients were admitted on Tuesday evening to the health facility in Newham, east London, which was created in just nine days to help cope with the pandemic.
A spokeswoman declined to say how many people were being treated at the custom-built field hospital at the ExCeL Centre in the capital's Docklands.
Opened by Prince Charles on Friday and named after nursing pioneer Florence Nightingale, it will need an army of up to 16,000 staff in clinical and ancillary roles to keep it running.
This evening the @RoyalAirForce and @Ldn_Ambulance practiced a patient transfer. Speed and efficiency come naturally to our emergency responders 🏃#ThankYou for helping us to treat the people that need us, when they need us most #LondonTogetherpic.twitter.com/7kbefBvm4f
— NHS Nightingale London (@NightingaleLDN) April 7, 2020
With more than 80 wards containing 42 beds each, the facility will be used to treat Covid-19 patients who have been transferred from other intensive care units across London.
Those who are admitted to the hospital will already be on a ventilator and will remain at the Nightingale until their course of ventilation is finished, the hospital's chief medical director has said.
Coronavirus patients suffering from other serious conditions – such as cardiac issues – will be cared for at other specialist centres.
Staff will be able to sleep at nearby hotels once they finish their shift, the hospital's director of nursing, Eamonn Sullivan, said – though they can also choose to go home.
Contractors and around 200 military personnel worked to get it up and running in just over a week.
NHS chief executive Sir Simon Stevens has called its construction "nothing short of extraordinary".
He added: "Now we are gearing up to repeat that feat at another four sites across the country to add to the surge capacity in current NHS hospitals."
Other Nightingale hospitals are due to open in Bristol, Harrogate, Birmingham, and Manchester.
The ExCeL centre has said it will not charge the NHS for use of the exhibition space after the initial deal included some contributions to costs.
The Sunday Times reported the complex, owned by Abu Dhabi National Exhibitions Company (Adnec), was charging the NHS between £2 million and £3 million per month to use the space.
But Adnec boss Humaid Matar Al Dhaheri said: "The venue was offered rent free from the initial conversation with the NHS, and Adnec Group will ensure the ExCeL London partnership comes at no cost to the NHS."