Prince William said he and wife Kate are "making sure the children understand all the sacrifices" frontline workers are making as they care for growing numbers of Covid-19 patients.
In a video call to staff at Homerton University Hospital in East London, he thanked them for their hard work and asked how they were coping with the experience.
WATCH: Prince William talks to George, Charlotte and Louis about the 'sacrifices' made by NHS workers
The Duke said: "A huge thank you for all the hard work, the sleepless nights, the lack of sleep, the anxiety, the exhaustion and everything that you are doing, we are so grateful. You are all in my thoughts.
"Catherine and I and all the children talk about all of you guys every day, so we're making sure the children understand all of the sacrifices that all of you are making so thank you so, so much.
"Good luck, we are all thinking of you."
William spoke to staff at Homerton University Hospital during a video call
In the past week, the hospital has seen its highest number of admissions since the crisis began, with more than 200 COVID patients currently being cared for and staff being reallocated to new roles to manage the surge in cases.
Dr Carlo Prina, Consultant Physician and Clinical Lead for Acute Ambulatory Care, told William things are worse than during the first wave of the virus.
He said Covid patients are now being treated on surgical, medical and paediatric wards and medical staff and trainees from other specialisms had been drafted in to help care for them.
But he added: "Our medical and nursing workforces have never been more stretched but never been more together as a group, so the cohesiveness, the commitment to patient care is a wonder to behold and it’s a wonderful thing to see."
The Cambridges showed their support for Clap For Carers last year
Alesia Parker, Matron in Acute Services, told the Duke: "We are supporting each other through this difficult time.
"It does feel worse than the first wave, it is a lot to take on but I think we are doing a good job at it."
And Nazia Ahmad, Occupational Therapist at the hospital, said a "Wobble Room" had been created for staff to relax using funds from NHS Charities Together, of which William and Kate became joint patrons of in December 2020.
The funds had also paid for breakfast boxes for hospital and community staff and a new break out room for A&E staff.
The Duke said: "It's good that you and your team are keeping your spirits high and I always find that having some sort of sense of humour through everything is very important, otherwise we all go mad."
Catherine Pelley, Chief Nurse, told William that the arrival of the vaccines had brought hope, adding: "But the support we need is stay at home, help us - because that will get us all out of this whatever our role is and we will get society out of this."
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