Last week, we reported that Prince Philip, 99, had been hospitalized after he told doctors he was feeling ill, and doctors decided to send him to the hospital for “observation and rest” just to be safe. Now, a sad update has come in about this situation, as it’s been revealed that Philip will need to remain hospitalized for several more days.

“The Duke of Edinburgh remains at King Edward VII’s Hospital where he is receiving medical attention for an infection,” Buckingham Palace said in a statement, according to Entertainment Tonight. “He is comfortable and responding to treatment but is not expected to leave hospital for several days.”

This comes after a royal source said that Philip was able to walk into the hospital without any assistance, and that his illness is not related to COVID-19. Both Philip and Queen Elizabeth, 94, received their COVID-19 vaccines last month.

Royal expert Katie Nicholl spoke out on Monday to say that Philip “is still in good spirits.”

“He was visited over the weekend by his son, Prince Charles. It’s very unusual for members of the royal family to visit other members in the hospital, largely because it causes panic and pandemonium in the press,” she said. “But we’ve been told that Charles, once he had visited his father, returned to Highgrove, that’s about two hours from London, which would, if anything, suggest that his father is in stable condition.”

“Prince William [also] commented on his grandfather today (Monday) on an engagement. When asked how he was doing, he said he was OK with a wink, because he couldn’t smile behind his mask,” Nicholl continued. “He said the doctors are keeping a close eye. We understand that the Duke [of Edinburgh] is going to remain in the hospital probably for a couple more days as a cautionary measure, so that he can be closely observed by his team of doctors.”

Royal biographer Penny Junor said jokingly that doctors and nurses at the hospital “would not want” Philip on their shift since he gets “irritated” by people fussing over him.

“I think he (Prince Philip) can be quite blunt and I think if he felt people were fussing over him he could be quite outspoken about that,” Junor said. “This is a man who doesn’t want any fuss made of his 100th birthday, so the fact he’s in hospital and getting some fuss made of him will really irritate him.”