The head of the government’s test-and-trace service and a senior NHS boss have become the latest senior figures in the pandemic response to announce they are self-isolating over potential coronavirus infection. Dido Harding, who heads the NHS test-and-trace service, posted an image from the app saying she needed to self-isolate, writing: “Nothing like personal experience of your own products … got this overnight. Feeling well. Many hours of Zoom ahead.” Later, NHS England’s medical director, Stephen Powis, told a Downing Street briefing he was self-isolating after a member of his household tested positive. “I am on Zoom today, I can’t join you in Downing Street and that’s because a member of my household recently tested positive for Covid, and on the instructions from test and trace I am self-isolating,” he said, adding that he was “completely asymptomatic and perfectly fine”. It follows the announcement on Sunday that Boris Johnson had been forced to stay inside Downing Street after holding a meeting with Conservative MPs, one of whom later developed coronavirus. Harding has been told to isolate until 26 November. While the self-isolation period is 14 days, it begins from the last close contact with the person who has contracted coronavirus, rather than from the moment of alert. The test-and-trace app previously told Harding’s husband, the Tory MP John Penrose, to self-isolate after potentially coming into contact with someone who has coronavirus. The service informed Johnson by email after the MP for Ashfield in Nottinghamshire, Lee Anderson, attended a meeting at Downing Street on Thursday morning, developed Covid symptoms and had a positive test. On Wednesday, Johnson was to take prime minister’s questions via video link, which has never been done before. A series of other Tory MPs at the meeting have also been told to self-isolate. Anderson and two others had posted photos of themselves at the event, standing about a metre from Johnson, with neither person wearing a face covering. Penrose did not attend the Thursday meeting, and Downing Street sources suggested the cases were not connected. Penrose, the Weston-super-Mare MP, tweeted: “It never rains but it pours … my NHS app has just gone off, telling me to self-isolate, which I’m doing. No symptoms so far *crosses fingers*.” Asked at the time whether he had spoken to his wife about it, he told the PA news agency: “We are trying to make sure we are doing it by the book, if I can put it that way. Her NHS app has not gone off so it’s someone I have been in contact with rather than her.” Johnson is in self-isolation until Thursday next week, but has been allowed, after consultation with health officials, to work in his No 10 office, reaching it via the garden from his flat. The prime minister was seriously ill with coronavirus in April, but has tested negative this time. Harding, the former head of the telecoms group TalkTalk and a Conservative peer, is also the interim head of the National Institute for Health Protection, the planned successor to Public Health England. Her role at test and trace has come in for criticism. Data released last week revealed the system was continuing to struggle to reach much more than 60% of the close contacts of people who tested positive for coronavirus. Government figures published on Thursday showed 60.4% of close contacts in England were reached through test and trace in the week ending 4 November. It was the fourth week in a row the figure had been around 60%, having dropped from 77.2% during the week ending 16 September.