Question 2: So what about this new “delta plus” that’s spreading in the U.K.? Scientists have named it “AY.4.2.” And it now accounts for more than 6% of the cases there. Does that mean it’s more transmissible than the current version of Delta dominating in the U.S.?

“No one knows yet,” says virologist Jeremy Luban at the University of Massachusetts Medical School. “It’s too early to really know.”

That’s because there isn’t enough data yet to measure its transmissibility. “That said,” Luban adds, “if it is more transmissible, it’s likely to be a small increment.”

Hanage estimates that it’s likely about 10% more transmissible than the original version of delta.

Remember, delta is already super contagious. So adding 10% more likely won’t change the behavior of the variant dramatically. (For instance, say you have a supercharged engine on your truck, if you bump up the turbocharge by 10% more, it’s not that much more supercharged.)