Foreign Office minister James Cleverly says England could have to have a fourth national lockdown.
Speaking to Sky News Mr Cleverley said future restrictions could not be ruled out.
He said: “We do want it to be the last lockdown, that’s what we’re working towards.”
But he added “no one can predict with complete certainty” what the virus will do.
Mr Cleverly said: “We are taking the right action, we are doing the right things and we very much hope that this will be the last lockdown.
“We can’t give complete 100% certainty because viruses don’t work like that.”
Mr Cleverly said it would be “wrong” for him to speculate on whether summer holidays will be allowed this year.
Speaking to BBC Breakfast, he said: “The Prime Minister will be setting out exactly what restrictions we are able to ease and when in as much detail as he is able.
“But we cannot give guarantees because that is not how viruses work. Our vaccination programme, our current set of restrictions have been effective, we know that. We are currently assessing how effective and what the implications might be of certain options.
“But ultimately we want to open up society, the economy as much as we are able but only on the condition that it is safe to do so.”
On summer holidays, he added: “I get how frustrating this is, it’s completely natural. We all want to get a break from this, I get that. But it would wrong for me to start speculating now.
“We are assessing the numbers, we are making a judgment based on the science and we will be making an announcement on Monday. I can’t go further than that.”
Infectious disease expert Dr Mike Tildesley has warned about reopening “too quickly” and seeing the virus reproductive R number rising again.
He told BBC Breakfast: “We do know any form of reopening will cause the R number to go up so that needs very very careful monitoring.
“The vaccination campaign is going very, very well… but where we need to be careful is if we open too quickly and don’t allow the vaccination programme to help us along the way, we run the issue of things resurging a little bit.
“I totally appreciate and understand the need to get children back in the classroom… the key thing for me is we need to do it in a way that schools don’t have to close again.”
On vaccination priority, he added: “I think there certainly is an argument once we have got through the key age groups to then look at potentially targeting a lot of our key workers.
“Not just teachers but actually all of our key workers on the front line, potentially to prevent them developing severe symptoms and enabling them all to sort of stay in school or stay in whatever key worker role they’re in.”