Health secretary Sajid Javid has tested positive for Covid-19, despite having received both vaccination jabs.
In a video message on his Twitter feed, the health secretary said that his symptoms were “very mild” and he was self-isolating at home with his family.
His initial positive test was provided by a quick-turnaround lateral flow test, and he is now awaiting confirmation from a PCR test, which is known to be more reliable.
His 10-day self-isolation with his family extends to Monday 26 July.
Mr Javid’s positive test sparked renewed calls for Boris Johnson to halt his planned relaxation of coronavirus restrictions in England on Monday, when legal requirements to socially distance and wear face-coverings will be lifted.
The health secretary was photographed on Friday leaving 10 Downing Street after apparently having a meeting with Boris Johnson, sparking concerns of a new coronavirus scare at the top of government.
He visited a care home in south London on Tuesday and attended the chamber of the House of Commons on Wednesday to open the debate on the Health and Social Care Bill, though it is not clear whether he was infected at that point.
A positive PCR test would trigger an effort by NHS Test and Trace to identify contacts who may have been infected.
Ministers, officials and Whitehall staff who have met the secretary of state over the last 48 hours now face the prospect of being called or “pinged” by the smartphone app over to be told that they too should go into self-isolation.
Mr Javid, 51, said: “This morning I tested positive for Covid. I’m waiting for my PCR result, but thankfully I have had my jabs and symptoms are mild.
“Please make sure you come forward for your vaccine if you haven’t already.”
Mr Javid said he took the test after feeling “a bit groggy” on Friday night.
“I’m now self-isolating at home with my family until I get the result of the PCR test,” he said.
“I’m grateful that I’ve had two jabs of the vaccine, and so far my symptoms are very mild.”
He urged anyone who has not yet taken up the offer of vaccines to “get out there and get them as soon as you can”.
And he added: “If, like me, you might feel a bit groggy, or you think might have come into contact with someone who’s positive, please also take a lateral flow test too.
“If everyone plays their part, you’re not only protecting yourself and your loved ones, but you’re also safeguarding the NHS and helping to preserve our way of life.”
Mr Javid is the latest in a string of senior government ministers and officials to be struck by Covid-19, including his predecessor as health secretary Matt Hancock and prime minister Boris Johnson, who spent three days in intensive care last year.
Liberal Democrat health spokeswoman Munira Wilson said: “I really wish Sajid Javid, his team and family are well, and all those he has been in contact with over recent days, including visits.
“This shows no one is safe from this deadly virus. The government needs to rethink its reckless plans for Monday.
“By easing all restrictions with cases surging, they are experimenting with people’s lives. Right now, they are pursuing a strategy of survival of the fittest, where the young and clinically vulnerable will be left defenceless.”
Scientists warn that two doses of vaccine do not provide blanket protection to everyone from infection with Covid-19.
Analysis by Public Health England shows that both the AstraZeneca and Pfizer vaccines offer better than 90 per cent efficacy against the dominant Delta variant of the virus after two doses, meaning that some of those with double jabs will still suffer “breakthrough” infections – though these are usually mild.
BBC presenter Andrew Marr revealed that he was infected at the G7 summit in Cornwall in June, despite having received two vaccine doses.
