Preliminary genomic characterisation of an emergent SARS-CoV-2 lineage in the UK

Figure 2 seems to show an extremely large number of mutations suddenly appearing in the new strain, effectively 1 year's worth of evolution in one go. The paper hypothesises that this could possibly happen in a single immunocompromised patient which carries the virus for months.

It would seem enormously critical to know how well the immune response from developed vaccines deals with this strain. Given they are are mostly targeted against the spike protein and the bulk of the mutations of the new strain are within the spike protein (in some cases are directly associated with evading human immune response), it seems possible (even if unlikely) that it might significantly reduce their effectiveness.

I wonder how quickly this can be experimentally established?

From what I've read so far, the structure of spike proteins seems to not have change, the virus just expresses many more spike proteins on its viral shell requiring more antibodies to neutralize and possibly allowing easier ACE2 docking.

How significant is the lineage?