Rosena Allin-Khan criticised the government for failing to adopt World Health Organisation (WHO) guidelines – that people with the disease should stay at home for 14 days even after their symptoms disappear.
Instead, the prime minister and the health secretary – quoting NHS advice – have both said they will go back to work just seven days after testing positive.
“This is deeply worrying,” Ms Allin-Khan told The Independent. “I just don’t understand why we don’t play it safe and follow the WHO guidelines.”
The GP, who has drawn praise for heading to the frontline of her local London hospital to help it cope with the crisis, added: “I will make this point every single day until government advice changes.
“The WHO are clear: you can be infectious for 14 days after symptoms stop, so seven days of isolation just doesn’t cut the mustard.”
After Mr Johnson revealed he had been struck down with the virus, No 10 made clear he would only remain holed up in Downing Street for one week.
Similarly, Mr Hancock tweeted: “From next Thursday, once I'm out of self-isolation and I hope with no more symptoms, then I'll be able to get back stuck in and into the office where necessary.”
Chris Whitty, the chief medical officer, who is also infected, will also emerge from isolation after just one week.
But the WHO guidelines state: “People infected with Covid-19 can still infect others after they stop feeling sick, so these measures should continue for at least two weeks after symptoms disappear.
“Visitors should not be allowed until the end of this period.”
The advice was put out a fortnight ago, by Dr Tedros Ghebreyesus, the WHO’s director-general and its frontperson in tackling the global response to the pandemic.
Furthermore, UK victims of the virus are only being told to isolate for seven days from the onset of symptoms – while the WHO recommends isolation for 14 days after symptoms go.
The controversy comes after the government was strongly criticised for failing to follow the organisation’s plea to “test, test, test” to get on top of the outbreak.
Instead, only patients admitted to hospital with severe symptoms, and those in care homes where there is an outbreak, are being tested – although NHS staff now will be.
Downing Street has been asked to respond to the criticism that ministers and advisers are failing to follow international guidelines.
The NHS’s advice on isolation says it need only be for 14 days if “you live with someone who has symptoms”, from the day those symptoms appear.
“This is because it can take 14 days for symptoms to appear,” the NHS website states.