Part of the 646-bed hospital scheme, which has been plagued by delays, will open to provide care for patients recovering from the virus.
The temporary Covid-19 facility, constructed by Laing O’Rourke, has capacity for 65 patients in what will become the acute medical care unit once the hospital is completed.
The wider hospital rebuild, which started in 2014, is intended to replace the existing buildings and create one of the largest emergency departments in the North West of England.
It was due to complete in 2017 but has suffered delays linked to the collapse of its original main contractor Carillion, as well as a plethora of structural issues.
The project is now expected to cost at least £724m, compared with £350m in the original business case, according to a damning National Audit Office report published in January.
The hospital NHS trust has now set a revised completion date of 2022.
Construction firm Laing O’Rourke took over as main contractor after Carillion’s collapse, while a £20m tender is out for remediation work to sub-standard cladding on part of the building.