What is the 'delta plus' variant of the coronavirus?

It’s a relative of the delta variant, identified by British scientists last month.

Because it isn't a variant of interest or concern, it has not yet been officially named after a letter of the Greek alphabet, like the other worrisome variants.

Scientists are monitoring the delta-related variant - known as AY.4.2. - to see if it might spread more easily or be more deadly than previous versions of the coronavirus.