Education Secretary Nadhim Zahawi has failed to rule out fresh school closures in January as fears mount over the spread of the Omicron variant.
Mr Zahawi could not guarantee that all schools will be open everywhere next term - but said he would do "everything in my power" to keep children in class.
Ministers have repeatedly said that closing schools again would be a last resort after repeated lockdowns caused massive disruption to children's learning.
Asked whether he could guarantee no schools would be shut, Mr Zahawi told the BBC's Andrew Marr Show: "We are absolutely working to make sure that all schools are open, that they're protected.
"I will do everything in my power. We are still learning about this variant.
"We know that a booster works. Get boosted, protect yourself, protect your community and let's get through this and transition this from pandemic to endemic."
Last month, Mr Zahawi insisted that closing schools was "absolutely" the last possible option.
But fears are mounting about the spread of the new Omicron variant, with reports of at least two outbreaks in schools.
Mr Zahawi confirmed on Sunday that there are "cases in hospital with Omicron" and warned that tens of thousands of Brits could end up needing hospital treatment.
The Education Secretary also failed to rule out extending the vaccine rollout to primary age children following reports health officials are gearing up to offer jabs to young kids.
He said: "There is no plan at the moment to vaccinate primary school children for the reason that the Joint Committee on Vaccination (and Immunisation, JCVI) is still looking at the evidence as to what level of protection it would offer."
The Medicines and Healthcare Products Regulatory Agency (MHRA) is expected to announce that jabs are safe for children, while the JCVI is examining whether to recommend vaccines for kids, according to the Sunday Times.
The European Medicines Agency approved the Pfizer jab for 5 to 11-year-olds last month.
The MHRA said: "Pfizer has stated that they are applying to the MHRA for an extension to their Covid-19 vaccine authorisation that would allow use in five to 11-year-olds.
"Further details on the timing of this submission would be for Pfizer to provide.
"We are committed to providing safe, timely access to treatment for UK patients, and will continue to prioritise our Covid-19 evaluations.
"This includes any decision on use in under-12s. Any such decision would be subject to our robust regulatory standards.
"In the meantime, we are looking at the data from other countries to ensure that when an application is received, we are making the best decision for children in the UK."
It comes after a damning report by Ofsted found that nearly every child in England had fallen behind at school due to Covid.
It warned that loneliness, boredom and misery had become "endemic" - and some children had developed physical and mental health problems due to the disruption.
Chief Inspector Amanda Spielman said there were children "who sadly are safer in school than out of it" as she warned that further shutdowns risk more cases like Arthur Lanbinjo-Hughes.
The six-year-old was abused and killed at home in Solihull last year.
