LONDON — The U.K.'s prime minister and health minister announced Friday they had tested positive for coronavirus and the country's chief medical officer is self-isolating with symptoms.

The U.K. government has faced criticism in recent weeks for its initial reluctance to implement strict lockdown measures imposed by many other countries and for what critics describe as a lack of clarity in its messaging about how citizens can help prevent the spread of the virus.

However, a YouGov poll published Friday suggested public support for the government's handling of the crisis continues to rise, with 72 percent now saying the U.K. is handling the issue well, up from 59 percent in a week.

The prime minister said in a social media video that he was experiencing mild symptoms, including a temperature and a persistent cough, but was well enough to continue to lead the U.K.'s response to the pandemic.

"Be in no doubt that I can continue, thanks to the wizardry of modern technology, to communicate with all my top team to lead the national fight back against coronavirus," Johnson said.

All three men have been in repeated contact with other senior figures, including Cabinet ministers and advisers, in recent days. On Wednesday, Johnson faced his weekly question session in the House of Commons and sat very close to many in his Cabinet.

Johnson’s official spokesperson said the prime minister would self-isolate in No. 11 Downing Street.

Johnson received his positive test result just hours after he was seen standing outside No. 10 Downing Street clapping in support of health workers, alongside — though more than 2 meters away from — Chancellor Rishi Sunak.

Shortly after Johnson's announcement, Health Secretary Matt Hancock, who had been expected to give a press conference in Westminster this evening, also said he had tested positive for the virus and would be self-isolating at home for a week.

“Upon medical advice I was tested and that test has been positive so I’ll be self-isolating here until next Thursday,” Hancock said. “Fortunately for me the symptoms so far have been very mild so I’ve been able to carry on with the work, driving forward the U.K.’s response.”

Later in the afternoon, the U.K.'s Chief Medical Officer Chris Whitty tweeted that he would be self-isolating for seven days after experiencing symptoms.

Johnson’s official spokesperson said the prime minister would self-isolate in No. 11 Downing Street. He has his flat above the building, which also houses the chancellor's private office. Sunak has moved out of his office, which will now serve as the prime minister’s workspace while self-isolating.

No. 11 can be effectively sealed off from No. 10 and No. 12 Downing Street, and government documents and meals will be delivered to the door for the prime minister to collect, the spokesperson said. Full videoconferencing equipment has been installed in the office.

The prime minister’s fiancé, Carrie Symonds, who is pregnant, posted on social media on Thursday that she was self-isolating, but it is not clear if she is currently living with the prime minister. Johnson’s spokesperson declined to comment on Symonds’ circumstances or condition. Following Public Health England advice for those who get symptoms, Johnson will be self-isolating for seven days.

Johnson, who would also typically have weekly audiences with Queen Elizabeth II, has not seen the monarch in person for “a significant time."

Johnson and Hancock would have had contact with numerous key figures working on the U.K.’s coronavirus response, leading to concerns that the virus could now be circulating throughout the top levels of government. The spokesperson said No. 10, as a workplace, had been observing the official social distancing advice for staff to work from home unless absolutely necessary, and to keep at least 2 meters apart from other people.

“The advice to staff here and also to the prime minister’s colleagues is that they don’t need to do anything in terms of self-isolation unless they begin to suspect they have symptoms, in which case they should follow the Public Health England advice,” the spokesperson said. They added that they were not aware of any other No. 10 staff testing positive for the virus, but confirmed that some had already self-isolated after developing symptoms.

Johnson, who would also typically have weekly audiences with Queen Elizabeth II, has not seen the monarch in person for “a significant time” and has been holding the weekly sessions by telephone for at least the past two weeks, the spokesperson said.

Cabinet Office minister Michael Gove said at the government’s daily Downing Street press conference on Friday afternoon (held yards away from where the prime minister is self-isolating) that the fact Johnson had “succumbed” was “a reminder that the virus does not discriminate, we are all at risk.”

The prime minister on Friday chaired a meeting with businesses and researchers, via video-conferencing, aimed at increasing testing capacity for frontline health workers, Gove said. He remained in contact with his ministers and officials by the same means.

The U.K., which on Thursday saw the number of people who have died in its hospitals after contracting coronavirus increase to 759, is bracing for cases to continue increasing over the coming days.

Chief Executive of NHS England, Simon Stevens, speaking alongside Gove, said there were currently more than 6,200 patients with confirmed cases of coronavirus in hospitals in England, that 33,000 hospitals beds had been set aside for the increase in cases, and that two further field hospitals would be set up, one in Birmingham and one in Manchester, with others to follow. A new hospital — NHS Nightingale — is already being set up in London, which will initially treat 500 patients, with capacity able to rise to 4,000 if necessary. The equivalent of 50 hospitals’ capacity had been set aside to treat coronavirus patients, Stevens said.

“Unfortunately pressure on the NHS is going to intensify in the coming weeks, there’s no doubt about that," he said, adding that additional coronavirus testing for NHS frontline workers would begin to be rolled out next week, starting with intensive care staff, emergency department staff, ambulance and GP services.