According to recent reports, Prince William contracted Covid-19 earlier this year.
It is believed the Duke of Cambridge tested positive in April at a similar time to his father, Prince Charles.
According to the Sun, which first reported the story, Prince William, 38, kept his diagnosis private to avoid alarming the nation.
Kensington Palace, the office and home of Prince William, refused to comment officially.
According to the Sun, Prince William, second in line to the throne, did not tell anyone about his positive test result because “there were important things going on and I didn’t want to worry anyone”.
The prince was treated by palace doctors and followed government guidelines by isolating at the family home Anmer Hall, in Norfolk, the paper added.
He reportedly carried out 14 telephone and video call engagements during April.
Prince Charles contracted coronavirus in March and spent seven days self-isolating in Scotland after displaying mild symptoms.
At the time, the Duchess of Cornwall tested negative for the virus and self-isolated for 14 days.
Prince Chrles, 71, later said he “got away with it quite lightly”.
During his first public engagement after recovering from coronavirus, the Prince of Wales said he had not fully regained his sense of taste and smell.
In April, PM Boris Johnson was admitted to hospital after testing positive for the virus.
The prime minister was moved to intensive care and later thanked healthcare workers for saving his life, saying it “could have gone either way”.
News of Prince William’s diagnosis comes days before England is due to enter a second national lockdown, with four-week measures to start on November 5.
On November 1, the UK recorded another 23,254 confirmed cases of coronavirus, bringing the total since the pandemic began to 1,034,914.
Another 162 people were reported to have died within 28 days of a positive test. It brings the total number of UK deaths to 46,717.