Charles, 71, spent seven days self-isolating at his home in Birkhall last month after testing positive for the virus and displaying mild symptoms.
He said: “I have to admit, at first I was quite concerned, he fits the profile of somebody, at the age he is at, which is fairly risky.”
William made the comments during a BBC interview to help launch a campaign to promote mental health wellbeing during the lockdown.
He and Kate have also narrated a powerful new film in support of Public Health England‘s Every Mind Matters platform, which includes new advice, focused on looking after people’s mental wellbeing during the pandemic.
The advice has been updated after new data shows over four in five Brits are worried about the effect that coronavirus is having on their life. More than half say the pandemic is affecting their well-being and nearly half reporting high levels of anxiety.
In the video, the royals can be heard saying: “All over the country, people are staying at home to protect the NHS and save lives. It’s not always easy. We can feel frustrated, miss loved ones or get anxious.
“So now, more than ever, Every Mind Matters. There are things we can all do to look after our mental wellbeing at this time.”
Launching the campaign, the Duke and Duchess of Cambridge said it was “vital” that people take care of their mental health as the country faces at least another three weeks in lockdown.
William and Kate urged everyone to follow the NHS ten point plan to keep mentally fit.
William said: “Staying connected, staying positive and being able to talk to friends and family is so crucial and having just some tips and some ideas as to how to tackle some of these strange feelings and difficult circumstances we’re finding ourselves in is really important, just to nudge us through these next few weeks.”
The future king also spoke of his admiration for NHS and frontline workers and the issues they face.
“In many of these cases obviously NHS workers, frontline workers are used to dealing sadly with very sad situations, death and things like that but I think the scale and the speed of what’s going on in hospitals, bearing in mind also the isolation, a lot of these patients are dying with no family members around them,” he said.
“I think for the NHS frontline workers that is very difficult, because they are there right next to the bedsides, looking after and caring for each and every patient in a critical condition and I think they take away that pain.
“And that sometimes that fear and loneliness that these patients have to go through, they’re the ones who absorb that and take it home to their families and I think again.”
Asked if the pandemic will fundamentally change who we are and what we value, Kate said she believed the country will view NHS workers differently after the crisis.
She said: “Yes, absolutely, I think what we’re saying now is the NHS and the frontline workers are doing the most extraordinary job and that’s really come to the forefront in the last few weeks and I think it’s going to dramatically change how we all value and see our frontline workers and I think that is one of the main positives that you can take from this.
“They do an extraordinary job it does unrecognised daily and now I think all of us as a nation can really see how hard they work and how vital their work is.”
Every Mind Matters is the NHS online advice of how to cope during the coronavirus outbreak. It states that having good mental health helps us relax more, achieve more and enjoy our lives more – and offers advice and practical tips to help look after wellbeing.