Professor Chris Whitty today told a Downing Street press conference that Covid-19 will continue to pose a threat to vulnerable people, like the flu or pneumonia, in the winters to come.
People still die of influenza despite an annual vaccine campaign, he added.
The threat of coronavirus will be with us for the next few winters, said Professor Whitty.
He says a swift lifting of coronavirus restrictions would lead to a spike in the R number.
Boris Johnson said: “This is not the end today but it is very clearly a road map that takes us to the end.”
He told a Downing Street press conference it would be a “one-way journey, we very much hope”.
Prof Whitty said there are still “very significant” numbers of people with coronavirus every day in the UK.
He added: “There is still a lot of people in hospital with this disease. This is not the end, but this is the point where we can have a steady, risk-based, data-driven opening up.
“But everybody must stick to the guidelines as they go through the different stages, because if we don’t do that then we will get to a stage where the rates go up very high and you’ll find there are people who are not protected by the vaccinations.
“These are not 100% effective, as the Prime Minister said.”
The Government’s chief scientific adviser Sir Patrick Vallance “completely” agreed with Prof Whitty, adding: “The caution of going every five weeks is very important because we need to measure so that we’re not flying blind on this.
“We need to know what the impact of the opening up steps are.”