There is "little evidence" of coronavirus being transmitted in schools, the education secretary has said.
Gavin Williamson said the government was being guided by the "best scientific and medical advice" as it boosts plans to reopen schools to all pupils in England next month.
He said: "The education and care of our children is a national priority. Ahead of the full return of all pupils to school in September, we are continuing to do everything in our power to ensure all children can be back in their classrooms safely, as this is the best place for them to be for their education, development and wellbeing."
Mr Williamson also confirmed an upcoming study would support the government's position on reopening schools.
"We have always been and will continue to be guided by the best scientific and medical advice.
"The latest research which is expected to be published later this year - one of the largest studies on the coronavirus in schools in the world - makes it clear there is little evidence that the virus is transmitted at school," he said.
The education secretary continued: “There is also growing confidence among parents about their children returning. This is down to the hard work of school staff across the country who are putting in place a range of protective measures to prepare to welcome back all pupils at the start of term.”
Care Minister Helen Whately told ITV News "schools will be safe for children to go back to" in September.
Ms Whately said: "We're determined to get children back to school."
"Back in March we had to close schools because of the peak of the pandemic. We know that teachers and parents have made huge efforts to continue homeschooling during the lockdown but that's just not the same as being in school, so we must see children back in school in September."
The care minister continued: "We know that the risks to children from Covid are really low, both on the one hand the risk of transmission in school is low, on the other hand in the event a child does get Covid, really low risk, so schools will be safe for children to go back to."
The prime minister said it is the “national priority” to get children back in class in England next month, but he has been warned by scientific advisers that “trade-offs” may be necessary to keep transmission down.
Teachers, scientists, opposition politicians and the children’s commissioner for England Anne Longfield have all called for improvements to testing before pupils return.
Ms Longfield welcomed Mr Johnson’s commitment to make children the priority after previously accusing ministers of treating them as “an afterthought”.
But she said regular testing of pupils and teachers, perhaps as frequently as weekly, could be needed even if they do not exhibit symptoms to keep transmission rates down.
“I think it needs to be as regular as it needs to be, to ensure that the infection is caught and identified as quickly as possible and then the tracking system can move on from that,” she told Times Radio.
Mr Johnson, who has spoken of a “moral duty” to reopen schools, is expected to focus on the minimal risk getting children back in class presents to their health and the potential dangers of keeping them away.
But National Education Union deputy general secretary Avis Gilmore called for ministers to “be clear” about support if a second wave of the virus strikes.
“Robust track, trace and test alongside health and safety checks in schools and colleges are necessary,” she said.
Another leading educators’ union has said it is drawing up a contingency plan which could undermine Mr Johnson’s hopes.
The Association of School and College Leaders said teachers might teach students on a week-on, week-off basis if there was a resurgence of coronavirus and schools were forced to limit the number of pupils attending, with the onus on parents to home school in the alternative weeks.
The union’s general secretary Geoff Barton said schools were “losing patience” with the government’s demand to have all children back in school next month while framing no back-up plan if this was not possible.
“If you want to limit the number of children on site or travelling to and from school, a big part of that is using rotas and the obvious way to do it is ‘week on, week off ’,” Mr Barton told The Daily Telegraph.
The latest tensions over Covid-19’s impact on education come as a European study suggested reopening schools was not a major danger in community transmission of the disease.
The European Centre for Disease Prevention and Control studied 15 countries, including the UK, and concluded: “There is conflicting published evidence on the impact of school closure/re-opening on community transmission levels, although the evidence from contact tracing in schools, and observational data from a number of EU countries suggest that re-opening schools has not been associated with significant increases in community transmission.”
Professor Sir Jeremy Farrar, the director of the Wellcome Trust – who is advising the government’s coronavirus response, said the “brief window” before schools reopen must be “used wisely” otherwise new restrictions will be needed.
He wrote in the Observer: “Most urgently, we need to ramp up testing. We are not where we need to be. We must improve contact tracing, so we’re identifying more cases and providing better, faster data locally.
“If we don’t, we may not be able to reopen schools without introducing new restrictions elsewhere. These are the trade-offs we face – if we do not act now.”