Coronavirus poses an “extraordinarily high” risk and people must take the stay at home rules seriously, England’s chief medical officer has warned, as new figures suggested one in 50 had Covid-19 last week.

Professor Chris Whitty said the country faced a “really serious emergency” as he urged people to adhere to the new England-wide lockdown measures, stressing that a “collective effort” was needed to bring cases down.

New figures released by the Office for National Statistics (ONS) suggested 1.1 million people in private households in England had Covid-19 between December 27 and January 2 – equivalent to 2.06% of the population, or one in 50 people.

They came as the number of daily confirmed cases of coronavirus in the UK topped 60,000 for the first time, while a further 830 people died within 28 days of testing positive for Covid-19 as of Tuesday.

Prime Minister Boris Johnson said that he had “no choice” but to plunge England into a third national lockdown in light of the figures, with the number of people in hospital with the virus in England higher than ever.

The latest data from NHS England showed there were 26,467 Covid-19 patients in hospital as of 8am on January 5 – a week-on-week increase of 21%. In London, the number stood at a record 6,816 patients, up 27% in a week.

Professor Whitty, speaking in Downing Street on Tuesday evening, said that because of the spike in people being admitted to hospital there will “inevitably” be an increase in the number of coronavirus deaths later this month.

And he told the press conference: “If we did not do all the things all of us must now do, if people don’t take the stay at home seriously, the risk at this point in time, in the middle of winter with this new variant, is extraordinarily high.”

He said the risk level will gradually decrease over time with measures being “lifted by degrees possibly at different rates in different parts of the country, we’ll have to see”, but said some restrictions may have to be introduced again next winter.

In a televised address on Monday, Mr Johnson announced stringent new controls – including closing schools to most pupils – in an attempt to prevent the NHS being overwhelmed by a surge in new infections.

The Prime Minister also said a plan to vaccinate 13 million of the most vulnerable people by mid-February could enable restrictions to be progressively eased from next month.

Mr Johnson told the press conference on Tuesday that, so far, more than 1.3 million people have been vaccinated against Covid-19 across the UK, including 23% of all the over 80s in England.

He also vowed to give daily updates on the vaccine rollout from Monday.

Prof Whitty said the vaccine timetable was “realistic but not easy”, and that the NHS would have to use “multiple channels” to get it out.

He also said it was important to follow the recommendations on vaccine ordering by the Joint Committee on Vaccination and Immunisation, despite pressure for teachers to be given greater priority.

“The reason for that is that that ordering means that we will have the maximum impact on the disease because the people that are by far the highest risk of dying will be vaccinated first,” he explained.

Chief scientific adviser Sir Patrick Vallance said it was possible the South African coronavirus variant may have some impact on vaccine effectiveness but is unlikely to “abolish” their effect.

He told the press conference that a possible change in the virus shape in the variant “theoretically gives it a bit more risk of not being recognised” by the immune system.

Sir Patrick said there was “nothing yet to suggest that’s the case” and that “the most likely thing is that this wouldn’t abolish vaccine effect” though it “may have some overall effect on efficacy but we don’t know”.

In other developments, Mr Johnson announced that the Government would be “bringing in measures to ensure that we test people coming into this country and prevent the virus from being readmitted”.

And he declined to guarantee that all children would be back in school before the summer holidays but said he is full of “optimism and fundamental hope” that things will be different in the spring.

Explaining his decision to impose another national lockdown, Mr Johnson said: “It was clear that we got to a situation where Tier 4 on its own couldn’t be relied upon to get the virus under control and that’s without really going the whole way and asking people to stay at home and, sadly, to close schools as well.

“That’s why we took the step that we did.”

All of the UK is now under stringent coronavirus restrictions. First Minister Nicola Sturgeon imposed a lockdown on Scotland for the rest of January, with a legal requirement to stay at home and schools closed to most pupils until February.

Schools and colleges in Wales will also remain closed until at least January 18 and move to online learning.

And in Northern Ireland – which is already under a six-week lockdown – “stay at home” restrictions will be brought back into law and a period of remote learning for schoolchildren will be extended.