Queen Elizabeth will deliver a special message to the UK and the Commonwealth on Sunday night as the death toll in the United Kingdom from the coronavirus pandemic rose to 3,605 and a new mega-hospital was inaugurated by Prince Charles on Friday.

Queen Elizabeth, 93, is also the head of the Commonwealth. A statement from the royal family said the message will be addressed to the UK as well as the 54 countries in the Commonwealth, including India.

The special address reflects the seriousness of the situation: it will be her only fourth such address at a time of national crisis during her 68-year reign, besides the annual Christmas Day message.

She previously delivered such special messages after the Queen Mother’s death in 2002, before the funeral of Diana, Princess of Wales in 1997, and during the First Gulf War in 1991. She also delivered a televised address to mark her Diamond Jubilee in 2012.

As the number of cases rose to 38,168 in the UK, Prince Charles opened the mega-hospital – called the NHS Nightingale Hospital – in the sprawling ExCel Centre in east London, which was converted into the hospital with 4,000 beds in nine days with the help of Britain’s armed forces.

More such hospitals in large public spaces are due to open in Cardiff, Glasgow, Manchester, Harrogate and Bristol. The prince of Wales, who recently recovered from the virus, inaugurated the hospital via video-link from his home in Birkhall, Scotland, saying he is “one of the lucky ones to have COVID-19 mildly”.

He said at the opening event: “It is without a doubt a spectacular and almost unbelievable feat of work in every sense, from its speed of construction – in just nine days as we’ve heard – to its size and the skills of those who have created it”.

“An example, if ever one was needed, of how the impossible could be made possible and how we can achieve the unthinkable through human will and ingenuity”.

Health secretary Matt Hancock added: “In these troubled times with this invisible killer stalking the whole world, the fact that in this country we have the NHS is even more valuable than before. It is the best of efforts. It is the best of the NHS”.

“And it is the best of Britain to come together in these difficult circumstances to put together such a facility, at such pace, that will be there for people so that we can give the very best care. And so that as a nation we can come through this crisis in the best way we possibly can”.