Δαφνη Ευτυχια Αρθουρος

"Unfortunately, we've got the delta variant. The CDC estimates the R0 of the delta variant as between 6 and 9, so let's see what happens to the calculation above if we use an R0 value of 8. We also need to consider how the delta variant affects the effectiveness of the vaccines. We don't know for sure how effective our vaccines are against delta, but the best estimates we have range at about 85 to 88 percent. Using a value of 85 percent (with 53 percent of the population susceptible), we find that the current Re for the delta variant in the U.S. might be as high as 5.

"You read that right-even after vaccinating half the po pulation, we still expect that people infected with the delta variant will, on average, infect more people than they would have with original virus. That's a big deal, and it's likely why the CDC has updated its guidance on masks. The delta variant is a game-changer and the current level of vaccination in the U.S. is not enough to stop it spreading.

"So, what do we do? We need to use all our tools from 2020, like masking, capacity limits, widespread testing, and quarantine and isolation of infected or exposed individuals[...]

"We may be masking for a while longer in an effort to get the Re of the delta variant closer to 1, or even below. But hopefully, if we all work together toward this goal, we can get to a point where masks are no longer needed to control the spread of COVID."

-- Eleanor J. Murray and Ruby Barnard-Mayers, "How We'll Know It's Finally Time to Stop Masking", 2021-08-06, Slate

An earlier veresion, Medium a day earlier and on Twitter a couple days before that, included this:

"We can also see that if Delta is really this bad, we'll need masks & other precautions for a long time to come.

"That's a real bummer & what's worse, we could have avoided this by doing a better job controlling infections last year.

"Let's not make the same mistakes twice!"