"He is comfortable and responding to treatment but is not expected to leave hospital for several days," Buckingham Palace said in a statement to the news outlet.
The 99-year-old monarch was admitted to London's King Edward VII's Hospital as a "precautionary measure" based on advice from his doctor on Feb. 16.
"He's a lot better," Prince Edward, Prince Philip and Queen Elizabeth II's youngest son, told Sky News of his father's condition.
He added, "He's looking forward to getting out, which is the most positive thing."
Philip, the husband of Queen Elizabeth II, spent a four-night stint in the hospital in December 2019 while undergoing treatment of an unknown pre-existing condition, NBC News notes.
Both Prince Philip and the queen received their first doses of the COVID-19 vaccinations in early January.