Sweden's Prince Carl Philip and his wife Princess Sofia Hellqvist have tested positive for COVID-19 after displaying mild, flu-like symptoms, the Swedish Royal Court announced on Thursday.

The couple have isolated themselves at home along with their two children but are feeling well "under the circumstances," the court said in a brief press statement.

Princess Sofia has volunteered at a hospital during the pandemic and said in a video posted on the royal couple's Instagram page earlier in the week that, apart from meeting colleagues and patients at the hospital ward, she is only spending time with immediate family.

Sweden's royal physicians have been put in charge of contact tracing and the King and Queen, as well as Crown Princess Victoria and Prince Daniel, are due to be tested on Thursday, though apparently none of them have displayed symptoms.