Last week, Dr. Anthony Fauci, head of the U.S. National Institute of Allergy and Infectious Diseases, and U.S. Sen. Rand Paul (R, KY) renewed their long-running argument over government policy and recommendations concerning reducing the transmission of the COVID-19 virus. This time, their fight centered on what should be done in cases where people had either received the full course of COVID-19 vaccine or else had contracted and recovered from the illness.

In both cases, it seems unlikely such people could transmit the disease to others, but that is not known for certain. Fauci believes such people should continue to wear protective facemasks to reduce their risk of spreading the disease to others. Paul believes otherwise, and even criticized Fauci, who has been vaccinated, for engaging in “theater” by continuing to mask.

The argument between the two physicians (Paul is an ophthalmologist) and its retelling in the press and on social media are just the latest rounds of the ongoing fight over “following the science.” That line is shorthand for a bundle of value judgments, including:

• Avoiding the negative health effects of COVID-19 outweigh all other considerations, including personal freedom, the economy, and the mental health effects of isolation.
• The consensus recommendations of medical experts outweigh all others’ recommendations.
• Former president Donald Trump’s pandemic policies were bad. (President Joe Biden, who understands this political reality, has repeatedly said his administration will “follow the science.”)

Last summer I wrote an essay for Cato’s Pandemics and Policy series about what science can and cannot do and the role it can play in public policy decisions. In a nutshell, science can explain relationships between cause and effect, no more. No normative conclusions about individual or collective decisions can follow directly from science. Instead, it is one input in individual and collective decision-making, along with costs, benefits, and other values.

Problem is, politicians and the public often want science to do more than it can. People in frightening situations in which they lack expertise want the world to be nicely delineated into what is “safe” and “unsafe.” Politicians don’t like making hard decisions when they’re in the public eye, so they like to hide behind the veil of science when they discuss why they favor some outcomes over others. Journalists contribute to this problem because they are accustomed to telling binary stories about “safe” and “unsafe,” and “good” and “bad,” rather than nuanced stories about tradeoffs and statistical shifts in health outcomes given various behaviors or exposures.

And, of course, some scientists like telling others what to do. Expertise is not only the ability to provide information; for some people it is political power.

Given all that, I was pleasantly surprised to see the New York Times display some highly nuanced thinking in this recent article on the origin of the six-foot social-distancing rule that has governed our lives during the pandemic. The rule originated from experts’ belief in the early stages of the pandemic that the virus was spread only by moisture droplets expelled by an infected person, and not likewise-expelled aerosols. Because droplets tend not to travel more than three to six feet (as opposed to aerosols that can linger in the air for a long period), the Centers for Disease Control and Prevention made the conservative recommendation to keep six-foot gaps between people.

But science is always updating, and so the six-foot rule has come under critical scrutiny. A recent natural experiment in Massachusetts compared districts that imposed strict six-foot distancing to those that required just three feet. The three-foot difference had no statistically detectable effect on COVID-19 case rates (though “the study’s authors acknowledged that they could not rule out the possibility that increased distancing provided a small benefit”) and there were fewer cases in schools than in the surrounding communities.

Even more striking in my view were the comments of a medical expert quoted in the article:

“There’s no magic threshold for any distance,” said Dr. Benjamin Linas, a specialist in infectious diseases at Boston University. “There’s risk at six feet, there’s risk at three feet, there’s risk at nine feet. There’s risk always.” He added: “The question is just how much of a risk? And what do you give up in exchange?”

… “I’ve evolved on this,” Dr. Linas said. “Last summer I felt like, ‘How are we going to explain to people that it’s six feet everywhere except for schools? That seems not consistent and problematic.’”

… “The benefits of school are different than the benefits of movie theaters or restaurants,” he said. “So I’d be willing to assume a little bit more risk just to keep [the schools] open.”

That sounds like what my colleague, Jeff Miron, and I argued in another Pandemics and Policy essay we wrote last year, but such statements usually come from economists and not infectious disease specialists. So “Follow the science” is now officially more complicated, even for doctors.

That’s progress.