Why does the Omicron sub-variant spread faster than the original?

Why does the Omicron sub-variant spread faster than the original? – Nature

Related:

Conflicting reports raise questions about whether any monoclonals work against Omicron’s sister variant.

Covid-19: What do we know about omicron sublineages?

We regret to inform you that we are now discussing subvariants – Vox

Sudden rise of more transmissible form of Omicron catches scientists by surprise.

Omicron’s sister variant spreads faster. So why did the one we call Omicron hit first?

[Preprint] Study suggests SARS-CoV-2 Omicron subvariants BA.2 is even more transmissible than the original variant.

BA.2 is like Omicron’s sister. Here’s what we know about it so far – The Conversation