“When polls said only about half of all Americans would take
a vaccine, I was saying herd immunity would take 70 to 75 percent,” Dr. Fauci
said. “Then, when newer surveys said 60 percent or more would take it, I
thought, ‘I can nudge this up a bit,’ so I went to 80, 85.”
“We need to have some humility here,” he added. “We really
don’t know what the real number is. I think the real range is somewhere between
70 to 90 percent. But, I’m not going to say 90 percent.”
Doing so might be discouraging to Americans, he said,
because he is not sure there will be enough voluntary acceptance of vaccines to
reach that goal.
(NY Times, Dec. 24, 2020, “How Much Herd Immunity is Enough.”)
Poll information about how many Americans would take a
vaccine is not evidence about how many people must be immune to achieve herd
immunity. By Fauci’s own account, his changed statement reflected not what the
scientific evidence showed but what he thought it prudent to tell people it
did. He had just publicly admitted, in the New York Times, that he was a
If he is not telling the truth, what is he doing?
Greyhound racing uses a mechanical rabbit, kept moving ahead
of the dogs to give them something to chase. Too close and they might catch it,
too far ahead and they might lose interest. The most plausible conjecture I can
come up with to explain Fauci’s account of what he is doing is that he is
following the same approach. In order to get people to do what he wants,
whether that is getting vaccinated or wearing masks, he has to persuade them
that it will do some good. If they believe the problem is almost solved, each
individual may figure that others will solve it and he can slack off, or may
decide to maintain precautions for a little while longer, at which point the
pandemic will disappear and he can stop. If, on the other hand, people believe
the solution is very far away, it is tempting to give up on it.
The solution, as for the greyhound race, is to keep
adjusting the estimate, subject to what you can get people to believe and how
close the rabbit has to be to motivate the dog to run.
In the short run this approach, like other versions of lying
to people for their own good — telling them, early in the pandemic, that masks
were useless to them, in order to save masks for medical personnel, or that a
lockdown would be only for a few weeks, in order to get people to go along with
it — looks attractive, a way of saving lives. In the longer run, it risks
persuading an increasing number of people that they should not believe what
authority figures tell them.
That is not a wholly bad thing, given that elite opinion, as
filtered through the media, is frequently unreliable, sometimes, as in this
case, deliberately dishonest. But there is a problem, currently illustrated by the
number of Americans who believe Trump’s claim that he really won the election.
The more people who distrust elite sources of opinion, the harder it is to get
people to coordinate on a common view of reality. If you cannot trust the
President’s advisor on the epidemic or, in other contexts, the New York
Times, to tell you the truth, why should you trust the people who tell you
that the election was, on the whole, honest, that although there were probably,
as in most elections, a few glitches here and there, there was nothing nearly
large enough to reverse the result?
If there are no elite information sources that you trust,
you might as well believe what you want to believe, as people are very much
inclined to do.
Postscripts on the Pandemic:
Fauci's quoted statements provide further evidence that what
he says reflects what he wants to tell people, not his scientific opinion.
“If you really want true herd immunity, where you get a
blanket of protection over the country ... you want about 75 to 85 percent of
the country to get vaccinated,” Fauci, the longtime head of the National
Institute for Allergy and Infectious Diseases, said in a live-recorded
interview with Rameswaram, the host of Today, Explained. “I would say
even closer to 85 percent.” (Vox, 12/15/20)
Current estimates imply that more than 100 million Americans
have had the disease already (91 million as of September, according to the CDC).
The same mechanisms that make vaccines work also imply that those people are
immune to the disease, at least for a while. If those people are put at the
back of the queue for vaccines, vaccinating 70% of the population will make
100% immune, at least if immunity does not turn out to expire in less than a
year. If we make no attempt to avoid vaccinating those who have had the
disease, 70% vaccinated should mean about 80% immune. Fauci is ignoring
that, presumably because taking account of it reduces the percent vaccinated that
he can claim we need.
There is, however, a reason to raise our estimate of the
requirement for herd immunity, having nothing to do with changes in what people
will believe. There are now two new and more contagious variants of the
disease, one first detected in the UK, one in South Africa. The more contagious
the disease, the larger the number of people who must be immune for herd
P.S. Someone pointed me at a recent piece by Bill Maher criticizing the media and the medical establishment for their failure to trust their audience with the truth about Covid.