I can give him a little bit of a pass on the mask guidance, because everything was so new at the time, but this is what really upset me. He admitted to intentionally misleading the public, because he didn't think that they were ready to hear the truth. How could anyone possibly trust a public health official after they've admitted to changing their numbers based off of polling data?
The R0 estimates suggest that a 60-70% vaccination rate is necessary to achieve herd immunity. This is the official position of the WHO. I don't think that Dr. Fauci is moving the goal posts based off new science, I think he's doing it to encourage more people to get vaccinated.
Dr. Fauci doesn't appear to have any problem with misleading the public if he feels he's doing it for the greater good. His opinion means nothing to me now, because I don't trust him to tell me the truth.
I can understand the skepticism. As for the science and the R0 you quoted, here is more from the NYT article I referenced.
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The original assumption that it would take 60 to 70 percent immunity to stop the disease was based on early data from China and Italy, health experts noted.
Epidemiologists watching how fast cases doubled in those outbreaks calculated that the virus’s reproduction number, or R0 — how many new victims each carrier infected — was about 3. So two out of three potential victims would have to become immune before each carrier infected fewer than one. When each carrier infects fewer than one new victim, the outbreak slowly dies out.
Two out of three is 66.7 percent, which established the range of 60 to 70 percent for herd immunity.
Reinforcing that notion was a study conducted by the French military on the crew of the aircraft carrier Charles de Gaulle, which had an outbreak in late March, said Dr. Christopher J.L. Murray, director of the University of Washington’s Institute for Health Metrics and Evaluation.
The study found that 1,064 of the 1,568 sailors aboard, or about 68 percent, had tested positive for the virus.
But the carrier returned to port while the outbreak was still in progress, and the crew went into quarantine, so it was unclear whether the virus was finished infecting new sailors even after 68 percent had caught it.
Also, outbreaks aboard ships are poor models for those on land because infections move much faster in the close quarters of a vessel than in a free-roaming civilian population, said Dr. Natalie E. Dean, a biostatistician at the University of Florida.
More important, the early estimates from Wuhan and Italy were later revised upward, Dr. Lipsitch noted, once Chinese scientists realized they had undercounted the number of victims of the first wave. It took about two months to be certain that there were many asymptomatic people who had also spread the virus.
It also became clearer later that “superspreader events,” in which one person infects dozens or even hundreds of others, played a large role in spreading Covid-19. Such events, in “normal” populations — in which no one wears masks and everyone attends events like parties, basketball tournaments or Broadway shows — can push the reproduction number upward to 4, 5 or even 6, experts said. Consequently, those scenarios call for higher herd immunity; for example, at an R0 of 5, more than four out of five people, or 80 percent, must be immune to slow down the virus.
Further complicating matters, there is a growing consensus among scientists that the virus itself is becoming more transmissible. A variant “Italian strain” with the mutation known as D614G has spread much faster than the original Wuhan variant. A newly identified mutation, sometimes called N501Y, that may make the virus even more infectious has recently appeared in Britain, South Africa and elsewhere.
