Op-Ed: Why Did Fauci Move the Herd Immunity Goal Posts?
— Scientists play a dangerous game when they tailor factual statements to promote policy goals
by Vinay Prasad, MD, MPH December 29, 2020

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Dr. Anthony Fauci speaks at a roundtable on donating plasma at the American Red Cross-National Headquarters
As a former National Institutes of Health fellow, I have a profound reverence for Anthony Fauci, MD, the director of the National Institute of Allergy and Infectious Diseases and a towering figure in American medicine. Fauci's contribution to biomedicine cannot be questioned. At the same time, recent statements by Fauci raise a thorny and important question for scientists, doctors, and public health experts: Is it acceptable to distort the truth to get people to do what you want them to do?

Late last week, Fauci told the New York Times that new science had changed his thinking on the herd immunity threshold -- but he also admitted that his statements were influenced in part by "his gut feeling that the country is finally ready to hear what he really thinks."

Specifically, the fraction of people who would need immunity to SARS-CoV-2 (either through vaccination or recovery from prior infection) to extinguish the spread of the virus was initially estimated to be 60% to 70%. In recent weeks, Fauci had raised the percentage: from 70% to 75%, and then to 75%, 80%, and 85%.

Allow me to quote verbatim from the article, titled "How Much Herd Immunity Is Enough?":

"When polls said only about half of all Americans would take a vaccine, I was saying herd immunity would take 70 to 75 percent," 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."

Of course, the herd immunity threshold is just an estimate, and the precise figure is contingent on population mixing and a host of other assumptions that may vary from location to location. The same threshold may be different in Rome than in Montana. For these reasons, Fauci has some wiggle room. But, the two undeniable admissions in the Times article are 1) Fauci is, to some degree, basing his statements on what he thinks the public will accept, and to what degree his rhetoric might help vaccination efforts, and 2) this is the absolutely stunning part, he is admitting this openly to a reporter for the New York Times!

This is not the first instance when Fauci made a public statement while considering, in part, what he believed people would do with the information. The first instance concerns masks and occurred during an interview on "60 Minutes" in March. Because these comments have been subject to much controversy, and are more nuanced than commonly reported, I will reproduce them in their entirety. I, personally, have transcribed them from a video, which runs for 1 min and 27 seconds.

Interviewer: There's a lot of confusion among people and misinformation surrounding face masks: Can you discuss that?

Fauci: The masks are important for someone who's infected to prevent them from infecting someone else. Now, when you see people and look at the films in China or in South Korea, whatever, and everyone is wearing a mask... Right now in the United States, people should not be walking around with masks.

Interviewer: You are sure of it? 'Cause people are listening really closely to this.

Fauci: Right now, people should not be ... there is no reason to be walking around with a mask. When you're in the middle of an outbreak, wearing a mask might make people feel a little bit better and it might even block a droplet, but it's not providing the perfect protection that people think that it is. And often, there are unintended consequences -- people keep fiddling with the mask, and they keep touching their face.

Interviewer: And can you get some schmutz sorta staying inside there?

Fauci: Of course, of course. But, when you think masks -- you should think of healthcare providers needing them and people who are ill. The people who -- when you look at the films of foreign countries and you see 85% of the people wearing masks, that's fine, that's fine, I am not against it; if you want to do it, that's fine.

Interviewer: But it can lead to a shortage of masks?

Fauci: Exactly, that's the point, it can lead to a shortage of masks for the people who really need it.

Later, of course, the public messaging would shift in support of universal cloth masks. This occurred in the absence of any substantive new mask studies. Critics would then point to this video as evidence that Fauci was dishonest; however, a full look at the remarks suggests the comments were nuanced. While he advised against community use, he later stressed he felt it was "fine." Fauci would later clarify that his words were chosen to prevent a run on masks -- so that healthcare workers would get first priority -- but some have used this interview to question his veracity.

Irrespective of your feelings in these specific cases, the core tension in both examples is whether we want scientific advisors and public health experts to report just the facts, as they see them, or do we want them to make the additional calculation of what the public would do with those facts, and use that to shape their comments, aiming to maximize the greater good?

I believe that in 2020, scientists and public health experts can only report the complete, unvarnished truth, as they believe it to be. We cannot and must not attempt to distort our ideas in an effort to generate responses we think might occur. I hold this position for four reasons.

1. The information gap no longer exists. Experts are not inherently smarter, more analytical, or logical than members of the lay public. Perhaps in the past, they preferentially had access to certain types of insider information. In the modern world, due to the internet, this information gap no longer exists. This dramatically changes the game.

An expert cannot distort the message to the public because too many in the public can directly interrogate the source material. In this case, that means: models estimating herd immunity thresholds or the data underlying community mask use, drawing their own conclusions. If an expert seeks to distort their view of the science to further a behavioral change amongst the public, the risk of detection is high -- at least by some in the public. As such, it runs the risk of immediate backlash and the ensuing loss of credibility.

2. It is not an easy game to play. Human beings are masterfully complex, and not easily predictable. In this case, Fauci's messaging in March may have been intended to prevent a run on masks, but it also may, to some degree, have contributed to masks becoming one of the most polarized issues of 2020, and, in many quarters, fostered a deep suspicion and distrust of Fauci.

Admitting openly that you are selectively presenting your view of the herd immunity threshold based on your reading of what the public is ready to hear, and the way in which that percentage might affect vaccine uptake is a bold and unprecedented statement. I am not a fortune teller, so I cannot imagine all the possible consequences, though I fear loss of trust and promotion of conspiracy theories is one.

The truth is that scientists are not trained to predict what people will do with varying pieces of information, in an effort to optimize outcomes. If they were, scientists would be blessed with optimal personal and professional relationships -- rarely quarreling with bosses, colleagues, or partners. Of course, that's not the case. Scientists, like anyone else, have difficulty knowing what you will do or say if you hear one thing versus another.

As such, the safest path is to always and only present the truth, as closest to the real views in your heart and mind.

3. Loss of trust is incalculable. Once it is revealed that any individual has presented information selectively to get the listener to change their behavior -- that person will forever be viewed through that lens: a calculating person. Is Fauci telling me this because the science supports it, because he believes it, or because he thinks hearing it might motivate a behavioral change on my part?

Personally, I don't see a way back from this situation. The moment the public believes that you might be withholding, selectively presenting, or distorting information to get them to behave a certain way, they will immediately put your comments through a translator. He might be saying this because it's what he believes, but what if he is saying it to change my behavior. What might that look like? What does he want my behavior to be, and what would it be if he told me something else? If that's the case, what might his real feelings be ... and on and on. The moment you enter this state in a relationship, there is no path back, it is over. Trust is irrevocably broken. A new spokesperson is needed.

4. Distortion steals power from the people and gives it to scientists. In a prior column, I argued that "Follow the Science" is an incoherent message. That's because science can tell you what might happen in varying scenarios, but science cannot tell you what to value. Science is necessary for sound policy, but it is not sufficient. Humans beings voicing their concerns and priorities, in concert with scientific guidance, is required to shape policy, and policy fundamentally belongs in the realm of politics and in the public square.

This means that scientists must not distort their view of a situation to get you to do the right thing because this robs you of your ability to decide what is the right and just and virtuous course. A scientist must always and only and indefatigably tell you the scientific truth, as best they see and understand it, but we all -- every last one of us who votes and participates in society -- we alone get to decide what the policy should be.

As I stated at the outset, I have profound respect for Fauci for his career of service, and like many, I am a fan of his clear public speaking. Yet, these two events force us to ask whether fact manipulation is acceptable.

I believe it cannot be. The public will not trust us, and should not trust us. People will put our statements through a reverse translator to try to deduce what we truly think, and it gives an unjustified power to scientists that belongs in the hands of people.

I can't control what others will do, but I can control myself. If I tell you what I think, I can't promise I am correct (in fact, like all mortals, I am occasionally wrong), but I can promise you that is, in fact, what I think.

Vinay Prasad, MD, MPH, is a hematologist-oncologist and associate professor of medicine at the University of California San Francisco, and author of Malignant: How Bad Policy and Bad Evidence Harm People With Cancer.

Last Updated December 29, 2020