Officials and ministers are still awaiting key data on the effectiveness of the four-week restrictions imposed across England, meaning a promised update to parliament on the next steps is unlikely to happen before late next week.

Scientists said that while they accepted the economic need for shops and hospitality businesses to reopen before the crucial festive season, the advent of seemingly effective vaccines meant people could consider postponing big family get-togethers.

“We really have to be careful that we don’t just focus on what is going to happen in six weeks’ time,” said Prof Catherine Noakes, a member of the government’s Scientific Advisory Group for Emergencies (Sage), who was speaking to the Guardian in a personal capacity.

“I know it is human nature to do that, but we will be better off planning for the longer duration and thinking of, actually, can we have a more low-key Christmas and new year this year and perhaps plan to do the bigger family celebrations in the summer when the risks are likely to be far lower for all sorts of reasons,” said Noakes, an expert in the transport of airborne pathogens from the University of Leeds.

Prof Gabriel Scally, a visiting professor of public health of the University of Bristol and a member of the Independent Sage group of experts, said he had little hope that the latest lockdown will quash the spread of the virus, given the spring lockdown had little effect in reducing infection levels in some parts of England.

“We know that the [last] and even more severe lockdown did not get the virus under control, so how can we expect that this will bring the virus under control given that some things have not changed?” he argued.

“How can we be in a good place by Christmas? I think it is impossible,” Scally said, adding that the aim should be for “a new, Covid-safe Christmas”, involving well-ventilated homes and lots of outdoor time.

“Plant your Christmas tree in the garden this year, and open your presents underneath the tree outside with family, or something like that,” he said.

Downing’s Street stated intention is that when the four-week, England-wide lockdown ends, the country will return to regionally tiered levels of restrictions. While no details have been given, the types of restrictions are unlikely to be identical to those that were in place before, and could be more robust.

Speaking at Monday’s Downing Street Covid press conference, Dr Susan Hopkins, an epidemiologist, said the previous lowest level, tier 1, had “little effect”, while the impact of tier 2 varied in different places.

Downing Street played this down on Tuesday, with Boris Johnson’s spokesman saying that even in tier 1 areas, the R, or reproduction, number of coronavirus was well below what it would be without interventions, “so the measures were having an impact”.

One government source said that while anecdotal evidence was that infection and hospitalisation rates were “moving in the right direction”, ministers were awaiting data from the midway point of the lockdown, which falls on Thursday.

A big decision for Johnson will be whether any strengthening of tiers could mean pubs, cafes or restaurants must remain closed, which could have a catastrophic economic before Christmas.

“That’s the challenge,” the source said. “We know that the big lever to pull to reduce R tends to be hospitality. Merseyside is a good example – when they moved into tier 3, it did have a noticeable impact. But that really isn’t palatable for vast swathes of the country, in economic terms.”

Christmas, they said, was being treated as a separate issue in terms of restrictions: “You’ve got to factor human behaviour into this. You can’t just say: ‘It’s winter, bringing elderly people indoors with high Covid prevalence and during flu season isn’t a good idea.’ You’ve got to acknowledge that it is Christmas.”

The latest Office for National Statistics figures showed almost 2,000 Covid deaths had occurred in England and Wales in the week to 6 November.

The total number of excess deaths – those occurring over and above the five-year average, and seen as an indicator of coronavirus fatalities – has reached 70,000, a figure that slowed considerably over the summer but is now accelerating.