The BMJ think that the new variant is more efficient than the original at infecting children:
Are children more susceptible to the new variant?
Yes, in comparison with the non-variant virus. Speaking at a press briefing, Neil Ferguson, director of the Medical Research Council’s Centre for Global Infectious Disease Analysis at Imperial College London and NERVTAG member, said that during the November lockdown in England there was a “general shift in the distribution of the virus towards children—for both the variant and the non-variant [virus].” This was expected, because of schools remaining open during the lockdown, he said, and among those aged under 15 there were slightly more cases of the variant virus in the community than the non-variant, though not significantly so.
But Barclay, who also sits on NERVTAG, said, “Let’s be clear. We’re not saying that this is a virus that specifically attacks children or is any more specific in its ability to infect children. But we know that SARS-CoV-2, as it emerged, was not as efficient at infecting children as it was adults. There are many hypotheses [as to why], but one is the expression of the ACE2 receptor that could be different in children. So if the [new variant] virus is having an easier time of finding and entering the cells, then that would put children on a more level playing field, if you like.”
www.bmj.com/content/371/bmj.m4944