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Queen Camilla has revealed her chest infection was a "form of pneumonia".

The 77-year-old royal no longer has the viral infection which forced her to miss a handful of engagements but is struggling with lingering fatigue and has ruled herself out of any of the outdoor activities planned for the two-day Qatari state visit, which got underway in London on Tuesday.

King Charles, 76, and The Prince and Princess of Wales, both 42, greeted the Emir of Qatar Sheikh Tamim bin Hamad Al Thani, 44, and his first of three wives Sheikha Jawaher at the outdoor Horse Guards Parade, and the queen was seen at Buckingham Palace getting out of her car beforehand and stayed inside to meet them at the Grand Hall.

Camilla came down with a chest infection after the king and queen's royal tour of Australia and Samoa and pulled out of duties on Nov. 5.

Despite previously confirming she would attend the 'Gladiator II' premiere in London's Leicester Square on November 13, she was advised to stay home.

Camilla was also absent from the king's official engagement to mark his 76th birthday November 14.

On doctors' orders, the queen missed the Remembrance Sunday (10.11.24) service at the Cenotaph.

A Palace spokesperson had said: "Her Majesty The Queen is currently unwell with a chest infection, for which her doctors have advised a short period of rest.

"With great regret, Her Majesty has therefore had to withdraw from her engagements for this week, but she very much hopes to be recovered in time to attend this weekend’s Remembrance events as normal.

"She apologizes to all those who may be inconvenienced or disappointed as a result."