Confusion is mounting over the government's new guidance on how long people need to isolate after receiving a positive COVID-19 result.
On Wednesday, the government announced it would cut the self-isolation period from 10 days to seven for those who take a lateral flow test on day six and day seven – as long as the results of both those tests are negative.
Sajid Javid said the move would "reduce the disruption from COVID-19 to people’s everyday lives" in the run-up to Christmas.
He added: "The UK Health Security Agency (UKHSA) have looked at this very carefully, and they are very comfortable that protection is provided by making this change so that people can leave isolation after day seven, as long as they've taken these two lateral flow tests and the results are negative."
However, the new rules are in conflict with the NHS and government's own advice, which says COVID tests should not be taken in the 90 days after testing positive.
At present, the NHS says: "If someone has tested positive with a PCR test, they should not be tested using either PCR or rapid lateral flow tests for 90 days, unless they develop new symptoms during this time – in which case they should be retested immediately using PCR.
"This 90-day period is from the initial onset of symptoms or, if asymptomatic when tested, their positive test result."
The rationale behind the guidance is that testing too soon after infection could result in a false positive result, leading to people isolating unnecessarily.
Watch: What are the new COVID self-isolation rules?
Yahoo News UK has also received a report that 119 – the COVID helpline – has advised that anyone still testing positive using a lateral flow on day 11 does not need to self-isolate.
When approached, the UKHSA has been unable to provide any written guidance as to how individuals should interpret government advice at the time of publishing.
The confusion comes amid warnings that the new guidance is risky.
Even when announcing the policy change, the guidance remains that anyone who leaves self-isolation early should limit close contact with people outside their household; work from home if they can; and limit contact with anyone at higher risk of severe illness if infected with coronavirus.
"The [calculation is] a bit like this: maybe 95% of people no longer infectious after 10 days. That might be 85% ish at 7 days, perhaps 90% at best," Professor Christina Pagel, from the Independent Sage group, said on Twitter.
"They are hoping that LFDs will catch those who are still infectious. LFDs will catch many, but not all.
"So yes - it's a riskier policy."
Epidemiologist Deepti Gurdasani, also from Independent Sage, was more critical.
"Yes, this is exactly what we need," she wrote on Twitter, ironically.
"Ending isolation for Omicron infected people early to encourage them socialising with others at Christmas in the midst of unprecedented levels of cases, and rising hospitalisations.
"I don't even know what to say anymore."
And human rights barrister Adam Wagner questioned the legality of the government's new guidance.
"It’s not even guidance, if you leave self-isolation having been notified of a positive PCR test, after less than 10 days, you will currently be committing a criminal offence," he said on Twitter.
"But the government say that once the guidance changes that will become a reasonable excuse for breaking the legal requirement to isolate for 10 days!
"Drives a coach and horses through the distinction between guidance and law."
The UK recorded its highest ever number of COVID cases on Wednesday, with 106,222 new infections reported in a 24 hour period.
Watch: Sajid Javid announces new self-isolation rules for England