Boris Johnson has admitted the level of COVID cases is “high” and he is “watching the numbers very carefully every day” – but insisted he is “sticking with our plan”.
This could include a return to mandatory mask wearing, a return to work from home guidance, or the introduction of coronavirus passports for some venues.
Some within the NHS have called for ministers to move to Plan B immediately after an eighth day in a row that the number of daily infections has been above 40,000.
Health Secretary Sajid Javid this week even predicted there could be as many as 100,000 COVID cases a day heading into winter.
But, asked what level of cases could trigger further action, Mr Johnson on Thursday said he would not yet be bringing in fresh measures.
“We’re watching the numbers very carefully every day,” the prime minister said on a visit to Northern Ireland.
“You’re absolutely right the number of infections are high. But we’re within the parameters of what the predictions were, what SPI-M and the others said where we would be at this stage given the steps that we’ve taken.
“So we’re sticking with our plan.”
Mr Johnson said the UK was in an “incomparably better” position than 12 months ago due to the “huge level of protection” now provided by COVID vaccines, which mean 90% of the adult population currently have coronavirus antibodies.
But he added the UK needed to “fortify ourselves further” ahead of this winter.
“The numbers are high, we can see what’s happening, we can see the increase, now is the time to get those booster jabs and also to vaccinate the 12 to 15-year-olds as well,” the prime minister said.
In a message to all those eligible for a booster vaccine, including the most vulnerable and all over-50s, Mr Johnson said: “When you get the call, get the jab.”
The prime minister stressed there was “certainly no shortage of supply” of COVID jabs with “huge quantities of vaccine” in the UK.
“Come forward and get it when your time comes – it’s a demand issue and we really urge people to come and do it,” he added.
Earlier on Thursday, former Conservative health secretary Jeremy Hunt urged ministers to consider whether to shorten the time that most people have to wait for a third booster jab from six months to five months after their second dose.
And Mr Johnson did not rule out shortening the time between jabs two and three for most people who are eligible for a booster vaccine, saying it was “an extremely important point”.
“On the issue of timing, all I will say is I think we just need to keep going as fast as possible,” he said.
Downing Street on Thursday confirmed that, should ministers decide Plan B was necessary, a House of Commons vote would be required to return to the mandatory wearing of face masks or to introduce the use of COVID certification for entry to certain venues.