Queen Elizabeth's Platinum Jubilee 2022: Queen says she is 'deeply touched' by jubilee celebration

Prince Andrew, the second-oldest son of Queen Elizabeth II, has tested positive for COVID-19, a royal source told ABC News.

Andrew’s diagnosis comes as the queen celebrates her Platinum Jubilee, marking 70 years on the throne. He was expected to join the royal family Friday at a national service of thanksgiving at St. Paul’s Cathedral, but will no longer attend, according to the royal source.

“After undertaking a routine test The Duke has tested positive for Covid and with regret will no longer be attending tomorrow’s service,” said the source.

As expected, Andrew did not appear with the royal family Thursday at Trooping the Color because he is no longer an active senior royal, including having returned his military titles and royal patronages to the queen earlier this year.

In February, Andrew agreed to settle a sexual assault lawsuit.

President Joe Biden and first lady Dr. Jill Biden tweeted a video message congratulating the Queen.

"Your Majesty, congratulations on your Platinum Jubilee. For 70 years, you've inspired people with your selfless devotion and service to the people of the United Kingdom and the Commonwealth," Biden said. "Throughout your reign, the relationship between the United Kingdom and the United States has grown stronger and closer than ever."

The first lady added her own well-wishes. "Throughout the years, the joy your visits to the United States have brought Americans, and your solidarity with the American people in times of tragedy, have deepened the friendship and profound connection between our countries," she said. "And Joe and I were so touched by the generosity and welcome you showed to us when we visited you at Windsor Castle last year, during our first visit overseas as President and First Lady."

"Congratulations, Your Majesty, and have a wonderful Platinum Jubilee celebration," she added.

They are 92 years apart in age, but Queen Elizabeth, 96, and her great-grandson, Prince Louis, 4, appear to share a close bond.

The queen was seen answering Louis’s questions and pointing things out to him while the two watched military jets fly overhead on the balcony of Buckingham Palace at the end of Trooping the Color.

Louis, one of the queen’s nine great-grandchildren, is the youngest child of Prince William and Kate, Duchess of Cambridge.

He joined his siblings, Prince George and Princess Charlotte, on the balcony and, earlier, in a carriage to travel to Buckingham Palace.

Britain’s royal family, led by Queen Elizabeth II, gathered on the balcony of Buckingham Palace to watch a traditional military flypast at the end of Trooping the Color.

Thanks in part to a weather-cooperating, beautiful sunny day in London, aircraft from the Royal Navy, British Army and Royal Air Force were able to fly directly down the length of the Mall and over the palace.

The queen, wearing sunglasses, watched the flypast with other members of the royal family, including Prince William and Kate’s children, Prince Louis, Prince George and Princess Charlotte, who were seen talking with the queen.

Down below the balcony, outside the palace gates, thousands of members of the public gathered to see the queen and watch the flypast, which is so fierce and low that onlookers say they can feel the ground rumble.