The PM admitted on Wednesday that getting kids back to class was tied to the national restrictions - and that children will not be going back after February half-term as hoped.
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."
The PM originally said the lockdown would be in place - and schools shut - until the middle of February but left the door open for it to be extended.
It will be a massive blow to parents and children hoping for schools would be able to reopen, as in the November lockdown.
But he promised: "The most important thing is to get kids back in school as soon as we sensibly can.
"That is what the government is determined to do."
He added: "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."
SHUT INSIDE Boris Johnson extends England’s lockdown for three MORE weeks & schools won’t got back until March 8 at earliest
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