Covid cases ‘could rise rapidly as isolation ends’

Covid cases could rise “rapidly” as isolation ends, Government scientists have warned, with some saying the next variant could be more deadly.

A sub-group informing the Scientific Advisory Group for Emergencies (Sage) suggested transmission could rise by between 25% and 80% if people “return to pre-pandemic behaviours and no mitigations”.

Prime Minister Boris Johnson is to set out his plan for living with Covid on Monday and is expected to axe the legal requirement to self-isolate after a positive test.

Free testing is also expected to be dropped at some point, with one minister suggesting testing had become a habit.

In its paper published on Friday but dated earlier this month and sent to Sage, the Scientific Pandemic Influenza Group on Modelling (SPI-M-O) said modelling by the University of Warwick showed that while the lifting of restrictions has “previously been gradual, a sudden change, such as an end to testing and isolation, has the scope to lead to a return to rapid epidemic growth”.

The university has also estimated that, at present, measures such as testing, self-isolation, mask wearing, increased home working and the avoidance of high-risk venues was reducing transmission by approximately 20-45%.

Elsewhere, the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) said in a paper for Sage on February 10 that there is a common misconception that new variants will be milder and that Omicron had been milder by chance.

It said “the milder symptoms in the human population, and in animal models, associated with the Omicron variant compared to previous variants, is likely a chance event”.

Nervtag said: “The next variant to achieve UK/global dominance is likely to have the same pathogenicity as previous variants.

“The loss of virulence as viruses evolve is a common misconception.”

The group added: “We remain concerned that a new serotype can emerge for which no current vaccine is effective.”