Prince Philip won't be leaving the hospital for several more days.
Buckingham Palace shared in a statement on Tuesday that the 99-year-old Duke of Edinburgh is continuing to undergo care at the King Edward VII Hospital in London, England.
"The Duke of Edinburgh remains at King Edward VII's Hospital where he is receiving medical attention for an infection," the statement reads. "He is comfortable and responding to treatment but is not expected to leave hospital for several days."
ET reported last week that Prince Philip was admitted to the hospital on Feb. 16 as "a precautionary measure" on the advice of his doctor after not feeling well.
A royal source told ET at the time that the husband of Queen Elizabeth II walked into the hospital unaided (after traveling to the facility by car) and was not admitted as an emergency. Philip's illness is not COVID-19 related, the source said, adding that he's been feeling unwell for a short period of time. Both Philip and the queen received their COVID-19 vaccinations last month and publicly shared the news to avoid inaccuracies and further speculation.
Additionally, in a new interview with ET on Monday, royal expert Katie Nicholl said that Prince 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," she 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."