I just published a long piece in the New York Times titled, “Why Did It Take So Long to Accept the Facts About Covid?” It’s about the seemingly small update the World Health Organization made last Friday to its webpage describing how COVID-19 transmits. The changes were just a few words and sentences, the update made quietly, without a lot of fanfare. 

I wouldn’t be surprised if few people not in the thick of the field are aware of it.

The revised [page by WHO] still emphasizes transmission in close contact but now says it may be via aerosols — smaller respiratory particles that can float — as well as droplets. It also adds a reason the virus can also be transmitted “in poorly ventilated and/or crowded indoor settings,” saying this is because “aerosols remain suspended in the air or travel farther than 1 meter.”

Just a few words, right? It may, however, be among the most important scientific steps taken during this whole pandemic, with immediate implications going forward. 

So I wrote a piece explaining its importance, and looking at why it took so long to come about. 

My piece was partially inspired by this video that I took less than two weeks ago in my first trip to New York in more than a year. It was a giant digital billboard in Times Square with a message by the World Health Organization, on how to protect ourselves against COVID-19. 

Here’s how it started:

Here’s how I describe it in my piece

First, “Hygiene” flashed, urging me to wash my hands, “practice respiratory hygiene,” avoid touching my face and wear a mask when necessary. Next, “Social distancing” told me to avoid close contact with people (illustrated by people separated by one meter), avoid shaking hands and stay home if unwell. Then “Medical help” advised me to follow local medical protocols.

I was stunned that the final instruction was “Stay informed.”

The message did not feel informative, to say the least. 

The billboard had not a word about ventilation, nothing about opening windows or moving activities outdoors, where transmission has been rare and usually only during prolonged and close contact. (Ireland recently reported 0.1 percent of Covid-19 cases were traced to outdoor transmission.)

How could it be so wrong, even after more than a year? It goes back to that seemingly simple update, the one major thing we got wrong, which people have mistaken about not just for this pandemic, but for more than a century.

I cannot summarize the whole piece here (it’s long!), but let me just say that it has multiple components, all of which are crucial. And even though the piece is long, what I wrote in that one piece barely scratches the surface of all of it. 

The topic of my piece is familiar to the readers of this newsletter. Why did it take so long to accept that SARS-CoV-2 was being transmitted through aerosols, respiratory particles that are small enough to remain suspended in the air, rather than through short-range respiratory droplets that could not travel more than a few feet because of their (bigger) size?

The reasons for this delay go back more than a century, to the fight against (incorrect but prevalent) theories that blame miasma—noxious odors, especially from rotting organic material—for diseases. While trying to counter erroneous but millenia-long folk-beliefs, some of the founders of public health and the field of infectious control of diseases around the world made key errors and conflations around the turn of the 20th century. These errors essentially froze into tradition and dogma that went unchanged and uncorrected for more than a century, until a pandemic forced our hand.

First, infection, which is easier at close range, was seen to be due to particles sprayed out of one’s mouth, which fell quickly to the ground but could land on people. The possibility that, even at close range, people were inhaling floating little particles (aerosols!) that could also travel farther, was discounted.

Second, this belief was strengthened by the worries —perhaps baked into the field, judging from many statements during this pandemic — that the vague, ominous threat from air would make people neglect hygiene measures like hand-washing, which was seen as more important because it was a way to guard against those short-range respiratory droplets.

Along the way to modern public health shaped largely by the fight over germs, a theory of transmission promoted by the influential public health figure Charles Chapin took hold.

Dr. Chapin asserted in the early 1900s that respiratory diseases were most likely spread at close range by people touching bodily fluids or ejecting respiratory droplets, and did not allow for the possibility that such close-range infection could occur by inhaling small floating particles others emitted. He was also concerned that belief in airborne transmission, which he associated with miasma theories, would make people feel helpless and drop their guard against contact transmission. This was a mistake that would haunt infection control for the next century and more.

Third, later on, there were other scientific errors that are almost like scribal errors in copying of manuscripts: measurements concerned with the size of infectious particles and where they could reach in the respiratory tract got conflated with size at which the particle could float, resulting in an error that stated the boundary as one twentieth what it should be. It remains incorrect to this day.

When the pandemic hit, we thus got told that the culprit was short-range particles—that’s what we always assumed for respiratory diseases that more easily transmitted at close range, unless proven otherwise through much effort. All other wrong-headed advice that we now understand to be incorrect flowed from that. Stay distant. No need for masks (which got updated later, but the theory underlying the resistance to masks was not updated until last week). No distinction between indoors and outdoors. And so on.

This assumption that these larger droplets that can travel only a few feet are the main way the disease spreads is one of the key reasons the W.H.O. and the Centers for Disease Control and Prevention didn’t recommend masks at first. Why bother if one can simply stay out of their range? After the C.D.C. recommended masks in April 2020, the W.H.O. shifted last June, but it first suggested ordinary people generally wear masks if physical distancing could not be maintained, and still said health care workers performing screenings in the community did not need to wear masks if they could stay that single meter away from patients. The W.H.O. last updated its mask guidance in December but continued to insist that mask use indoors was not necessary if people could remain separated by that mere meter — this time conceding if ventilation might not adequate, masks should be worn indoors, regardless of distancing.

Of course, the data did not fit this theory. Infections were happening mostly indoors, not outdoors, whereas droplets would be indifferent to existing indoors or outdoors since gravity is the same in both. Infections were occurring at longer distances, which droplets can’t travel along. Infection was happening subject to ventilation conditions, which don’t affect those projectile-like droplets. The superspreading was driving the pandemic, with a small percent of people responsible for more than 70 percent or more of infections, in clusters. This can easily happen in a disease driven by aerosol spread; in contrast, droplets aren’t very conducive to such superspreading.

Scientists who understand all this tried to raise the alarms going back to last March and April. They were rebuffed for almost a year. 

Last fall, under fire, the WHO assigned reviews of this topic to the very people who had loudly proclaimed their opinions for many months that the virus was being spread via respiratory droplets and not airborne methods. These “external”  teams were joined by people who held key roles at the organization and also had very public opinions on this. The reviews then used criteria that would not count as airborne, namely measles and tuberculosis — two undoubtedly airborne pathogens —  to decide we could not reach “firm conclusions” on the topic. 

The ancients believed that all celestial objects revolved around the earth in circular orbits. When it became clear that the observed behavior of the celestial objects did not fit this assumption, those astronomers produced ever-more-complex charts by adding epicycles — intersecting arcs and circles — to fit the heavens to their beliefs. Many kept up even after science advanced. Epicyles might seem quaint and archaic, but maybe they were more relevant even now than we would admit: 

In a contemporary example of this attitude, the initial public health report on the Mount Vernon choir case said that it may have been caused by people “sitting close to one another, sharing snacks and stacking chairs at the end of the practice,” even though almost 90 percent of the people there developed symptoms of Covid-19. Shelly Miller, an aerosol expert at the University of Colorado Boulder, was so struck by the incident that she initiated a study with a team of scientists, documenting that the space was less full than usual, allowing for increased distance, that nobody reported touching anyone else, that hand sanitizer was used and that only three people who had arrived early arranged the chairs. There was no spatial pattern to the transmission, implicating airflows, and there was nobody within nine feet in front of the first known case, who had mild symptoms.

So here we are, a year later. 

Things have moved forward, but the progress is not happening the way it should: by leaders and experts proclaiming loudly and openly what we have learned and what it means. This is important both practically, going forward as we face the rest of this terrible pandemic, and also on understanding how things get obstructed and how to address such bottlenecks. The silence may be partly because it is difficult for some people to face up to all this now, having gotten things so wrong for so long. Nonetheless, the historic responsibility is clear, and, besides, this is just the way science works, sometimes. Things go wrong, and then we learn more.

Some of the science behind this is in this article I co-authored in The Lancet (it is a short article so it is readable, but there are a lot more fascinating scientific details that have been published recently, and some on the way—more on that soon),

My piece is here, and I think it simultaneously one of the most important topics I worked and wrote about during this pandemic, simultaneously a source of fascination, but also despair but also hope, exactly because, things do improve. Eventually. I was able to put in a tiny amount of the history and the science, and even the narrative. There is so much more to this, and I could have easily tens of thousands of words even now (in fact, I wrote some of that but we did not put it in for obvious reasons: The New York Times is newspaper, not an outlet for serialized books)

The rest of it will be written though, and not just by me. This may well be one of the most important parts of not just this pandemic’s history, but a crucial case with implications for history of science as well on how we learn things, how we sometimes get stuck on the wrong thing, and what it takes to, finally, try to move on, for the better.