Princess Kate is expected to be "out of action for a long time", following her planned abdominal surgery.
Following her operation on January 16, the Princess of Wales is recovering at The London Clinic hospital.
In a statement released by Kensington Palace on Instagram, it was revealed that the Princess of Wales is "unlikely to return to public duties until after Easter."
To help with her recovery, Prince William has also decided to temporarily step back from royal engagements to look after his wife.
Lizzie Cundy says Kate's absence leave the monarchy 'vulnerable'
PA / GB News America
In another statement released by Buckingham Palace, it was announced that King Charles will also be hospitalised this week, after being diagnosed with an enlarged prostate, which is "benign".
The King has also had to postpone engagements for a "short period" until he is back to full health.
Speaking on GB News, host Nana Akua said the absence of possibly four senior royals makes the monarchy appear "vulnerable", as the King aims for a slimmed down firm.
Nana noted that there's now "not many" working royals left in the family, which has now been further impacted by Kate and Charles' health concerns.
King Charles has also been diagnosed with a benign enlarged prostate
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Cundy said: "From what I hear it was a very big operation, and she's really got to take her time to get well with this. So she's going to be out of action for a long time, maybe longer than we think. So it's very worrying.
"And sadly the news about King Charles, I think it was unbelievable he was so open about this illness. Never before has a royal been so open. And you know, one in eight men get this prostate problem."
Cundy then criticised Prince Harry for not speaking out about his family members since their announcements, as he made his first joint public appearance of the year with wife Meghan Markle in Jamaica.
Nana disagreed and admitted she is "not surprised" that the Duke and Duchess of Sussex have remained silent on the matter.
Lizzie Cundy says Kate Middleton will be 'out of action for a long time'
GB News
Nana told GB News: "Meghan has not yet gone to visit her father as far as we know, who is very ill and may well be dying potentially because he had a stroke.
"He's not a young man at all, and so I'm not surprised.
"Remember what happened with the whole interview on Oprah when Prince Philip was clearly dying again, they didn't bother with that one."
Cundy then added: "Prince Harry was called the spare, so they could call on him on times like they this when they would need him to step up to the plate, but sadly he's ruined it all."