Schools do not play a significant role in driving the spread of Covid-19 in the community, a study suggests.

Cases among teachers fell during the November lockdown – when schools in England remained open – particularly in regions with the toughest restrictions, according to epidemiologists at the University of Warwick.

Researchers say there is no significant evidence to suggest that children attending class, particularly in primary schools, is a major driver of outbreaks in the community in England.

In December, the data indicates a large rise in the number of absences due to confirmed infection in secondary schools in the South East and London, but such rises were not observed in other regions or in primary schools.

The researchers say the increased transmissibility of the new variant in these regions may have contributed to the rise in cases in secondary schools.

The study comes as Boris Johnson said no decisions have been made on whether all pupils in England can return to school at the same time.

The Prime Minister is preparing to set out his “road map” for relaxing measures on February 22, with March 8 earmarked for schools to start reopening to all pupils.

The preprint examines data on school absences in England from September to December 2020 as a result of Covid-19 infection – and how that varied through time as other measures in the community were introduced.

The research, which has yet to be peer-reviewed, found that cases in secondary school pupils increased for the first two weeks of the November lockdown in many regions before decreasing.

Author of the paper Dr Mike Tildesley, from the University of Warwick, said: “Our analysis of recorded school absences as a result of infection with Covid-19 suggest that the risk is much lower in primary than secondary schools and we do not find evidence to suggest that school attendance is a significant driver of outbreaks in the community.”

Dr Edward Hill, from the University of Warwick, said: “During the first two weeks of the November lockdown we observed an increase in pupil absence as a result of infection with Covid-19, yet in the following weeks the data indicates that in several regions there was no subsequent rise in Covid-19-caused teacher absence.

“It is important to note that our findings only refer to cases reported in school children and teachers, and do not provide an indication as to whether these individuals were infected within the school environment.”

But the researchers say careful continued monitoring of the potential impact on community incidence may be required as schools reopen to more pupils.

Speaking to journalists at a briefing, Dr Tildesley said: “I think with any form of relaxation we need to approach it with an element of caution. We do know that any form of reopening even with this evidence, whether it be schools or otherwise, will result in an increase in the R number.

“I would say a cautious stepwise approach in any setting is really what’s needed so that we can avoid a resurgence.”

Dr Tildesley suggested mixing should be kept as “low as possible” in other parts of society when children return to class, as he warned that relaxing controls “too rapidly” could increase the risk of having to close schools again.

He added that “local reactive measures” – which could include school closures – may be needed to avoid a rise in infections in regions.

Ministers have said reopening schools is their first priority, but reports have suggested a staggered approach may be taken, with secondary schools going back a week later than primaries.

On Monday, Mr Johnson told reporters that no decisions have been taken on that detail.

Dr Tildesley told reporters: “Given there’s uncertainty as to what will happen if we opened all schools – and in terms of whether we might go above 1 again (with the R number) – there is certainly an argument for slightly staggering it.

“So potentially thinking about maybe early years or primary schools and then easing back in might be something Government could consider, but, as I say, I also accept that this is more of a political decision and they could weigh up all of these other impacts of keeping certain children at home longer.”