That's a lot of mutations

[Knish]

17min and 16 sec into a research panel's Q&A vid: https://youtu.be/NKI__VxMaFo?t=1036

wasn't sars cov2 supposed to have an 'error checking' transcriptase? or is this still comparatively few vs other virus mutations?

[JimF]

It has error checking. But it also has a way of swapping out one genetic sequence for another, both of which have been error checked.
So the new mutation passes the error check too.

It is very smart.

[Jonazz]

Also: the more people who get infected, the bigger the odds of a new dangerous mutation.

[Joe_H]

Yes, large numbers of infected increases the number of mutations. Even if the error checking is 99.9999% or better at catching a change and blocking it, with hundreds of millions infected and whatever large number of the virus get created in each person, some changes are inevitable. Of those some will be viable and capable of replacing the original variant and spreading.