The Prime Minister on Wednesday announced he would set out the UK Government’s strategy for the “gradual and phased” easing of lockdown in the week beginning February 22.
Mr Johnson explained reopening schools was the top priority and he was hoping to do so on March 8 if the “economic and social restrictions” could be eased “then or thereafter”.
He said: "At this point, we do not have enough data to judge the full effect of vaccines in blocking transmission nor the extent and speed with which the vaccines will reduce hospitalisations and deaths, nor how quickly the combination of vaccinations and the lockdown can be expected to ease the pressure on the NHS.
"We will not persist for a day longer than is necessary, but nor can we relax too soon, because if we do we run the risk of our NHS coming under still greater pressure, compelling us to re-impose every restriction and sustain those restrictions for longer.
"So our plan for leaving the lockdown will set out our approach towards re-opening schools.
"If we achieve our target of vaccinating everyone in the four most vulnerable groups with their first dose by February 15 – and every passing day sees more progress towards that goal – then those groups will have developed immunity from the virus by about three weeks later, that is by March 8.
"We hope it will therefore be safe to commence the reopening of schools from Monday, March 8, with other economic and social restrictions being removed thereafter as and when the data permits – then or thereafter."
England’s schools are currently closed to everyone but vulnerable pupils and the children of key workers.
Mr Johnson’s commitment came during a Commons session that also saw the PM announce new measures to combat more dangerous strains of the virus coming into Britain, as well the number of people coming from high risk countries.
Under the new rules, travellers will be met at the airport and transported directly into quarantine, while those hoping to travel will have to apply to do so first.
This afternoon Home Secretary Priti Patel warned anyone found at the border without a good reason would be sent home or fined.