Camilla, 73, said of her 99-year-old father-in-law: "We heard today that he's slightly improving, so that's very good news. We'll keep our fingers crossed."
The Duchess' comments came as the Duke spent his 15th night in hospital. Prince Philip was transferred from King Edward VII's Hospital to St Bartholomew's Hospital on Monday.
WATCH: Prince Philip transferred to new hospital for further tests and treatment
In a statement on Monday Buckingham Palace said: "The Duke of Edinburgh was today transferred from King Edward VII’s Hospital to St Bartholomew's Hospital where doctors will continue to treat him for an infection, as well as undertake testing and observation for a pre-existing heart condition.
"The Duke remains comfortable and is responding to treatment but is expected to remain in hospital until at least the end of the week."
The Duchess shared an update about her father-in-law
Prince Philip spent 13 nights at King Edward VII's hospital in London after being admitted on 16 February as a "precautionary measure" after feeling unwell.
The Prince of Wales visited his father in hospital on 20 February, making a 200-mile round-trip from his home, Highgrove, in Gloucestershire.
The Duchess visited a vaccination centre in Croydon
The Queen and the Duke have been residing at Windsor Castle throughout the lockdowns.
The Duchess of Cornwall visited the community vaccination centre at St Paul's Church, Croydon, where she spoke with and thanked NHS staff and church representatives supporting the UK vaccination rollout.
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