In a decision to ease the lockdown on June 21st, just days away, Boris Johnson said the spread of the Delta variant is “seriously and seriously worrying”.
The Prime Minister is expected to announce a delay of up to four weeks in the final relaxation of restrictions in England, which will be launched on Jan.
During the G7 summit in Cornwall, he insisted that no decisions had been made before a formal announcement was made on Monday.
However, he made it clear that the situation had worsened since the beginning of the month with an increase in the delta variant, which was first discovered in India.
“It is clear that the Indian variant is more transmissible and it is also true that cases are increasing and the number of hospitalizations is increasing,” he told Sky News.
“Now we don’t know exactly how this will affect additional mortality, but there are clearly serious, serious concerns.”
When asked if he was less optimistic now than at the end of May, he said: “Yes, that’s certainly fair.
“We want to make sure the roadmap is irreversible, but you can’t have an irreversible roadmap unless you are willing to be careful.
“Some of the dates are still open, but we will make an announcement on Monday.”
His comments come as experts warned the government to be “careful” to lift lockdown measures entirely in England due to the surge in Delta variant cases.
Professor Peter Openshaw, a member of the Nervtag Advisory Group, said it was a “disappointing setback” that the variant seemed even more successful than the previous strains.
He told BBC Radio 4’s Today program on Saturday: “This Delta variant appears to be about 60% more broadcast than the (the Alpha variant).
“So it really has gone up a gear and that means we really have to double up to avoid losing all the advantage we have gained from the massive efforts that have been made so far.”
Ministers are considering lifting the easing of controls for up to four weeks as they battle to introduce the vaccine for younger age groups.
Mr Johnson told ITV News, “We are looking at all of the data, but we want to avoid another wave of deaths that could be prevented by making the vaccines work as they are.
“The vaccination program was absolutely amazing and there is no question that the people who are going to the hospital now are in different groups, younger groups than we saw in the first waves of the pandemic.
“But in the race between the vaccines and the virus, we may have to make sure that we give the vaccines extra legs.”
A final decision is expected to be made on Sunday before a formal announcement by the Prime Minister at a press conference the following day.
Secretary of State James Cleverly said it was “critical” that the country does not stumble at the final hurdle and that restrictions are lifted “safely”.
However, a delay – possibly until July 19 – will be a major blow to many companies, particularly in the hospitality and leisure sectors, who had their hopes for a full reopening this summer to make up for some of last year’s losses.
Scientists now estimate that 96% of all new coronavirus cases are attributed to the delta variant.
The latest figures from Public Health England (PHE) showed that 42,323 Delta variant cases had been confirmed in the UK, 29,892 more than the previous week.
It estimates that the strain is 60% more transmissible compared to the previously dominant Alpha or Kent variant and that cases double every four and a half days in some parts of England.