His comments come as ministers mull whether to scrap Plan B restrictions on January 26, following a sustained drop in cases. The UK reported 84,429 infections on Monday – down 40 per cent in a week.
Pressed on whether the Government should move ahead with relaxing curbs, Dr Nabbaro told BBC Breakfast: “Restrictions are making a difference because they reduce the number of contacts people have, and restrictions therefore are helpful and it’s important that there is no premature promising that restrictions will end at a particular time or we’ll be able to get back to normal at a particular time.
“I want to be hopeful but I want to do my best to be as clear with what I’m really seeing, which is where I need to continue to be cautious and I will be.”
He added: “I’m a public health person... I would not be making promises some time in the future because, once you make a promise, it’s super hard then to change what you’re going to do - you feel you’re kind of doing a U-turn.
“This virus is constantly evolving and it’s super hard to predict where it will be.
“We can say where we hope we’re going to go, we can say where we’d like to go, we can say what we think we need to do to get there - but making promises that we’ll do something on a particular date, I think, is unwise."
Earlier on Tuesday, SAGE adviser Professor Andrew Hayward said there are “very encouraging signs” of cases plateauing or dropping in some places, but nobody is sure whether they will stabilise at a very high level or dip down.
Prof Hayward, said he agrees that the “pandemic will end and we will move to a situation where we’re living with the virus continuing to transmit but causing much less disruption”.