Re-starting NHS services could take many months, experts say.
Everything from cancer care and routine surgery to district nursing services have been disrupted across the UK by the coronavirus pandemic.
At the end of April, ministers said it was time to restore services.
But three think tanks said reorganising services, coupled with the need for more personal protective equipment and extra cleaning, meant it would be some time before the NHS was back fully.
'Come forward for urgent care'
It comes as NHS bosses have once again urged patients to seek urgent medical treatment if they need it.
There is particular concern that patients who have suffered strokes and heart problems have stayed away because of fears over coronavirus.
NHS England clinical director for stroke Dr Deb Lowe said she and fellow doctors were "really worried" that the numbers seeking help for stroke care had gone down.
Figures due to be published on Thursday are expected to confirm A&E attendances in England have dropped dramatically since the outbreak began.
Monitoring of a sample group of A&E units by Public Health England suggested visits during April, which coincided with the peak of the pandemic, were close to half the level they were before the pandemic struck.
Referrals for cancer care have also fallen, while community services have had to be scaled back as staff have been redeployed and face-to-face contact has had to be restricted.
Macmillan Cancer Support chief executive Lynda Thomas said despite urgent cancer care being prioritised during the lockdown, services were still affected, while she fears some patients were put off seeking help.
'Cancer must not become the forgotten 'C' in this pandemic."
The think tanks – the Nuffield Trust, King's Fund and Health Foundation – said restoring services was going to take time.
They warned staff were exhausted because they had been working flat out and needed time to recover.
[contf] [contfnew]
bbc
[contfnewc] [contfnewc]