Talking to Entertainment Tonight, Nicholl added: "My understanding is that they've been keeping in touch through social media ... which must be incredibly hard for Meghan being so close to her mother.
"And equally difficult, one would imagine, for Doria because she hasn't been able to see Archie. But I am told by reliable sources that they're taking social distancing and the government guidelines very seriously indeed."
Harry and Meghan recently revealed their new charity is called Archewell, inspired by their son's name.
The couple said: "Like you, our focus is on supporting efforts to tackle the global Covid-19 pandemic but faced with this information coming to light, we felt compelled to share the story of how this came to be. Before SussexRoyal, came the idea of 'Arche' - the Greek word meaning 'source of action'.
"We connected to this concept for the charitable organisation we hoped to build one day, and it became the inspiration for our son's name. To do something of meaning, to do something that matters. Archewell is a name that combines an ancient word for strength and action, and another that evokes the deep resources we each must draw upon. We look forward to launching Archewell when the time is right."
