Schools are unlikely to reopen all at once when the national lockdown ends, the deputy chief medical officer has said.
Jenny Harries said on Tuesday it was “likely” there would be “regional separation”, with schools in some places opening before others.
Boris Johnson has said he would like schools back after the February half-term, but cautioned it would depend on the course of the coronavirus pandemic.
The prime minister added they would be the “very first thing” to reopen once lockdown measures lift.
Ministers have said England will return to its system of tiered regional restrictions once the national measures, which legally expire at the end of March, are lifted.
Speaking to the Commons education committee, Harries said it was impossible for the school reopenings to be “set in concrete” as “we cannot be absolutely sure of the virus”.
“On the broad epidemiology it is highly likely that when we come out of this national lockdown we will not have consistent patterns of infection in our communities across the country,” she said.
“And therefore, as we had prior to the national lockdown, it may well be possible that we need to have some differential application.”
Asked whether there could be a regional or phased system for reopening schools, Harries said: “I think it’s likely that we will have some sort of regional separation of interventions.”
She added schools would be at the top of the priority list to ensure that the balance of education and wellbeing is “right at the forefront”.
“Schoolchildren definitely can transmit infection in schools, they can transmit it in any environment – but it is not a significant driver as yet, as far as we can see, of large-scale community infections,” she said.
Pupils in schools and colleges in England, except children of key workers and vulnerable pupils, have been told to learn remotely as part of the lockdown.
But more than a fifth of primary school pupils in England were on-site last week during the latest lockdown, government figures published on Monday showed.
Overall, 14% of state school pupils were in class on January 13, which is higher than when schools were partially closed between March and May last year.
Figures from the Department for Education (DFE) show 21% of primary school pupils were on-site last week, while 5% of secondary school students were in class.