Earlier this year, more than two million people were asked to shield in their homes until August 1.
Under the plan signed off by Mr Johnson, up to 4.5 million people will be targeted under the new enhanced shielding programme, based on a combination of factors including age and particular risk factors that have been identified since March.
Government research has found that, among people already diagnosed with Covid-19, those aged 80 or older were seventy times more likely to die than those under 40. Officials have also said that people with diabetes, heart disease and dementia all appear to be at higher risk of death.
A Department of Health spokesman said: “We keep all aspects of our response to the pandemic under review and in line with the advice of our scientific and medical experts.
“Shielding for the clinically extremely vulnerable has been paused since the start of August in most of the country while average rates of coronavirus remain low. Shielding is still advised in specific areas of the country where prevalence of the virus is higher.”
Meanwhile, a poll by ORB International found that many young people are failing to follow Government guidelines on social distancing, with one in five (22 per cent) of 18 to 24-year-olds admitting that they are failing to distance from friends and family outside their households.
Overall, 11 per cent of people said they were not, for the most part, still following the rules. One in five (21 per cent) of respondents agreed that gathering with friends and family outside their households was no longer a risk to their health, rising to one in three of those aged between 18 and 34.
The findings come after Matt Hancock, the Health Secretary, urged young people not to “kill your gran” by failing to observe the rules amid a significant increase in infections.