People should use lateral flow tests hours before they meet up with others in light of the apparent infectiousness of the Omicron variant, a public health expert has warned.
Irene Petersen, a professor of epidemiology at University College London, said official advice should be updated as those infected with Omicron “may switch from being non-infectious to infectious within hours”.
The NHS Covid Pass requirement for venues such as nightclubs, state a negative test result will be valid for 48 hours.
And current government guidance recommends taking a test “if you will be in a high-risk situation that day”.
However, Professor Petersen said that this guidance is “not good enough” to keep people safe.
“We’re seeing so many examples now where people have taken a test a day before and then when they take one the day after they are positive,” she told the Sunday Telegraph.
“Omicron is very, very fast, so the test result expires very quickly. It is hours that we are talking about now.”
She warned that the scenario of people going to events and saying they are double vaccinated and have taken a test may not be enough.
“That doesn’t help if you took that test yesterday morning, because in the meantime you may have become infectious,” she added.
Health Secretary, Sajid Javid, warned earlier this month that the “window between infection and infectiousness may be shorter” for Omicron, compared to the Delta variant of Covid-19.
The latest figures from the UK Health Security Agency showed there had been 10,059 additional confirmed cases of the Omicron variant reported across the UK, bringing the total confirmed cases of the variant across the four nations to 24,968.
The variant’s rapid spread means tougher restrictions could soon be introduced.
However, The Times reported officials were drawing up plans for a two-week “circuit breaker” in England which would include a ban on indoor socialising after Christmas.
A report in The Sun said stricter measures could be imposed after Boxing Day, although it added that the contingency plan had not yet been presented to ministers.
It comes after scientific advisers to the Government said hospital admissions with the Omicron variant in the UK are “probably around one-tenth of the true number” due to a lag in reporting.
The “situation update” from the Scientific Advisory Group for Emergencies (Sage) on Thursday was published on Saturday and said that it is “almost certain that there are now hundreds of thousands of new Omicron infections per day” in England.
Asked about a possible tightening of restrictions after Christmas, a Government spokesman said they will “continue to look closely at all data and keep our measures under review”.