he Duke of Edinburgh is "slightly improving" but he "hurts at moments", the Duchess of Cornwall has said.
On a visit to south London, Camilla said of her 99-year-old father-in-law: "We keep our fingers crossed."
Philip, the nation's longest-serving consort, has spent 15 nights in hospital - his longest ever stay.
He is undergoing testing for a pre-existing heart condition and treatment for an infection after being moved by ambulance to St Bartholomew's Hospital in the City of London on Monday.
The hospital move heightened concerns for the duke, who will turn 100 in June.
Camilla's comments were reported by broadcasters covering her engagement on Wednesday morning at a community vaccination centre in Croydon.
Philip was said to be "comfortable" after his arrival at St Bartholomew’s, with Buckingham Palace saying "doctors will continue to treat him for an infection, as well as undertake testing and observation for a pre-existing heart condition".
The Palace added that the duke was responding to treatment, but was expected to remain in hospital until at least the end of the week.
He was initially admitted to the private King Edward VII's Hospital on February 16 as a precautionary measure after feeling unwell.
Four days later, he was visited by his eldest son the Prince of Wales, who made a 200-mile round trip and stayed for around 30 minutes.
Philip has spent most of lockdown residing at Windsor Castle with the Queen for their safety, alongside a reduced household of staff dubbed HMS Bubble.
The Queen and the duke, who have been married for 73 years, received their first Covid-19 jabs in January.
Meanwhile, the Duchess of Cornwall said she suffered no side effects from her Covid-19 jab, and it was painless even though she dislikes needles.
Camilla, who had her first coronavirus jab last month, like the Prince of Wales, spoke to NHS staff, administrators and volunteer marshals, and met members of the public receiving their injections.
The duchess, who was wearing a medical face mask and a pink tweed Anna Valentine coat, chatted to Dr Agnelo Fernandes, a GP leading the vaccination process, about her own vaccination.
"No side effects and it didn't hurt and I'm not a lover of needles," Camilla remarked.
She joked to staff: "Have you had anyone sitting down and then legging it out of the room yet? No? Good."
The duchess asked: "Are you having a lot of numbers coming in? What are your main problems?"
Told misinformation was an obstacle, Camilla replied: "Social media is an issue, isn't it?
"The misinformation put out there - it just helps talking to your friends and colleagues about how easy it was.
"It may encourage them. It's good to see the community leading by example."
"We have a high degree of hesitancy as well. But despite that we have been doing really well."
He said they were dealing with a rate of about 30% of people who did not want to take the vaccine.
"We are working on different ways of combating this, with community leaders and faith leaders, giving them information to make an informed choice," Dr Fernandes added.
"There is so much disinformation and conspiracy theories. I am on several BAME groups and what is out there, particularly on social media, is just shocking."