The country is still on track for the safe lifting of coronavirus restrictions, Government scientific advisers believe, though they have urged people to carry on working from home.

Experts predict a rise in coronavirus cases as restrictions ease, but a future wave is not expected to be as big as last winter and should not put intense pressure on the NHS.

Prime Minister Boris Johnson echoed the thoughts, telling reporters he “can’t see any reason” to delay the remaining steps along the road map.

Speaking in Hartlepool, Mr Johnson said: “I think that it’s been very important for our country that we’re able to get through Covid as fast as we can.

“I think we’ve got to always bear in mind that this thing isn’t over.

“I think the epidemiology is very encouraging at the moment but we’ve got to continue to be cautious, and we will continue with the cautious but irreversible steps of the road map.

“I can’t see any reason now to delay any of the steps that we’ve got ahead of us, but that’s going to be our programme.”

Modelling produced for the Government suggests people will not go back to pre-pandemic levels of contact with others as restrictions lift in May and into the summer.

Asked if people should continue working from home once limits on social contact are lifted on June 21 in England, one Government scientist source said there was no reason to return to an office full-time if work could be done at home.

They said it made sense for people to carry on working from home as it reduced the levels of contact people have, and this had been supported by many business who are allowing hybrid or home working.

The source said that even last August, people were still only at about 50% of pre-pandemic contact levels with other people.

They added that measures this summer which could help to keep case rates in check included home working, good ventilation in buildings, and tables being kept apart.

A decision on whether masks on transport will be needed will be made over the next month or so depending on coronavirus rates, they said.

On the issue of booster vaccines in the autumn, the source said people are likely to be given a shot from the existing range of vaccines.

A vaccine dedicated to tackling variants may not be available until the end of the year and may not even be needed, they added.

The comments come as data shows that Covid-19 infections in England and Wales have hit their lowest level for eight months.

Around one in 1,180 people in private households in England had Covid-19 in the week to May 2, down from one in 1,010 the previous week, according to the latest estimates from the Office for National Statistics (ONS).

It is the lowest figure since the week to September 5, when the estimate stood at one in 1,400.

The percentage of people testing positive for coronavirus is estimated to have decreased in all regions of England except in Yorkshire and the Humber, eastern England and London where the trend is uncertain, the ONS said.

In Wales, around one in 2,070 people in private households is estimated to have had Covid-19 in the week to May 2 – down from one in 1,570 in the previous week, and the lowest since the week to September 5.

In Northern Ireland, the estimate is around one in 750 people, up from one in 940 in the previous week.

Meanwhile, the estimate for Scotland is around one in 760, down from one in 640 and the lowest since estimates began for Scotland in October.

Elsewhere, Public Health England (PHE) has upgraded the B.1.617.2 coronavirus variant first identified in India to a variant of concern.

This is based on evidence which suggests the variant is at least as transmissible as the Kent variant, though it does not carry a specific E484K mutation that has been worrying experts.

According to PHE, cases involving the variant have increased to 520 from 202 over the last week and almost half the cases are related to travel or contact with a traveller.

The variant cases are spread across the country. However, the majority are in the North West (predominantly Bolton) and London, where there has also been increased transmission.

Weekly data shows that Bolton in Greater Manchester had the second highest Covid-19 case rate in England for the seven days to May 2, up from 48.0 to 85.2.

PHE said there was currently insufficient evidence to indicate that any of the variants detected in India cause more severe disease or make current vaccines any less effective.

Dr Susan Hopkins, Covid-19 strategic response director at PHE, said: “The way to limit the spread of all variants is the same and although we are all enjoying slightly more freedom, the virus is still with us.

“Keep your distance, wash your hands regularly and thoroughly, cover your nose and mouth when inside and keep buildings well ventilated and meet people from other households outside.

“If you are told to get a test, if you have any symptoms at all or have been in contact with someone who has tested positive, please make sure you get tested too.”

The Prime Minister said that tracking of the Indian variant was “absolutely ruthless”.

He told reporters: “What we’re doing there is making sure that we are absolutely ruthless in the surge testing, in the door-to-door tracking of any contacts.

“At the moment we’re looking carefully at the way the Indian variant seems to function, we don’t see any evidence that it is resistant to the vaccines or in any way more dangerous.”

Dr Jenny Harries, chief executive of the UK Health Security Agency, told a Downing Street press conference on Friday evening that communities where the Indian coronavirus was spreading would be advised to take extra precautions beyond what might be permitted nationally in terms of socialising.

“We really do want people to be extra cautious,” she said.

Current evidence suggests that the two other variants detected in India are not variants of concern.