[cstejerean]

With early variants 60-70% may have very well been sufficient. As we get variants that can spread more easily that raises the bar on what we need for herd immunity. I don’t think a lot of people appreciate just how much worse Delta has been in this regard. Fingers crossed we don’t get an even worse variant.

[tqi]

But NYT article where the quote originated is from December 2020 (ie months before the Delta variant was officially named and more than half a year before it hit the US), so I don't think that is an explanation for why the number changed.

I think the most likely explanation is that public health officials believed that citing a 60-70 number would feel more achievable, and thus encourage people to continue masking/distancing until a vaccine was available. If they has said 85% in May 2020, maybe people would have thought it was hopeless and just opened up immediately.

Whether they judged correctly or not, I don't think it was a good idea to bend the truth because it erodes trust in institutions.

[knodi123]

That may very well be. However, there's no need to wonder whether Fauci was being totally frank the entire time, because he has outright said that he knowingly gave a so-optimistic-its-a-lie estimate at first, in an effort to avoid intimidating people.