In a post on their @sussexroyal Instagram account, the couple said they would be using the platform to share resources and post “accurate information and facts from trusted experts”.

They added they would also use it to help people learn measures they can take to keep themselves and their families safe and work with organisations that can help with “mental and emotional well-being”.

Their message came as it was revealed that US First Lady Melania Trump will urge Americans to wash their hands and keep their distance from one another to fight coronavirus in a new TV ad campaign produced with major broadcast networks.

ABC, CBS, NBC and other networks will air the public service announcements, which will also include other Trump administration officials and “communicate the most important ways Americans can protect themselves and those most at risk”, the White House said in a statement.

Nickelodeon will create a separate campaign for children.

The air time will be donated by media networks, the White House said.

Trump, a former fashion model, has avoided the public arena more than many first ladies. Her signature initiative has been a campaign called Be Best, which focuses on the safety and well-being of children.

Meghan and Harry, who are understood to be in their new home in Vancouver, Canada, having completed their final duties as senior royals earlier this month, said people are living in “uncertain times”.

Calling for unity, they said: “Now, more than ever, we need each other.”

They added: “We need each other for truth, for support, and to feel less alone during a time that can honestly feel quite scary.”

“Our willingness, as a people, to step up in the face of what we are all experiencing with COVID-19 is awe-inspiring,” they wrote.

“This moment is as true a testament there is to the human spirit.”

As well as sharing information and practical advice on maintaining physical health and wellbeing, the duke and duchess said they would be posting inspirational stories from around the world.

“We will focus on the inspiring stories of how so many of you around the world are connecting in ways big and small to lift all of us up,” they said.

“We are all in this together, and as a global community we can support each other through this process – and build a digital neighbourhood that feels safe for every one of us.”

They finished the post with the words: “We look forward to sharing more over the days and weeks to come…”

From March 31, Harry and Meghan will no longer use their HRH styles as they begin a life away from the royal family – mostly based in North America.

The couple have vowed to try and become financially independent and pay back the public funds used to renovate their former home of Frogmore Cottage in Windsor.

– AAP