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Guest Essay

Why Did It Take So Long to Accept the Facts About Covid?

May 7, 2021
Credit...Tomasz Lazar
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[10]Zeynep Tufekci

By [11]Zeynep Tufekci

Dr. Tufekci is a contributing Opinion writer who has extensively
examined the Covid-19 pandemic.

This article has been updated.

A few sentences have shaken a century of science.

A week ago, more than a year after the World Health Organization
declared that we face a pandemic, a page on its website titled
“Coronavirus Disease (Covid-19): How Is It Transmitted?” got a
seemingly [12]small update.

The agency’s response to that question [13]had been that “current
evidence suggests that the main way the virus spreads is by respiratory
droplets” — which are expelled from the mouth and quickly fall to the
ground — “among people who are in close contact with each other.”

The [14]revised response 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.”

The change didn’t get a lot of attention. There was no news conference,
no big announcement.

Then, on Friday, the Centers for Disease Control and Prevention also
[15]updated its guidance on Covid-19, clearly saying that inhalation of
these smaller particles is a key way the virus is transmitted, even at
close range, and put it on top of its list of how the disease spreads.

There was no news conference by the C.D.C. either.

But these latest shifts challenge key infection control assumptions
that go back a century, putting a lot of what went wrong last year in
context. They may also signal one of the most important advancements in
public health during this pandemic.

If the importance of aerosol transmission had been accepted early, we
would have been told from the beginning that it was much safer
outdoors, where these small particles disperse more easily, as long as
you avoid close, prolonged contact with others. We would have tried to
make sure indoor spaces were well ventilated, with air filtered as
necessary. Instead of blanket rules on gatherings, we would have
targeted conditions that can produce superspreading events: people in
poorly ventilated indoor spaces, especially if engaged over time in
activities that increase aerosol production, like shouting and singing.
We would have started using masks more quickly, and we would have paid
more attention to their fit, too. And we would have been less obsessed
with cleaning surfaces.

Our mitigations would have been much more effective, sparing us a great
deal of suffering and anxiety.

Since the pandemic is far from over, with countries like India facing
devastating surges, we need to understand both why this took so long to
come about and what it will mean.

*

Initially, SARS-CoV-2 was seen as a disease spread by [16]respiratory
droplets, except in rare cases of aerosol transmission during medical
procedures like intubation. Countertops, boxes and other possible
fomites — contaminated surfaces — were seen as a threat because if we
touched them after droplets fell on them, it was believed the virus
could make its way to our hands, then our noses, eyes or mouths.

The implications of this were illustrated when I visited New York City
in late April — my first trip there in more than a year.

A giant digital billboard greeted me at Times Square, with the message
“Protecting yourself and others from Covid-19. Guidance from the World
Health Organization.”

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.”

That billboard neglected the clearest epidemiological pattern of this
pandemic: The vast majority of transmission has been indoors, sometimes
beyond a range of three or even six feet. The superspreading events
that play a major role in driving the pandemic [17]occur
overwhelmingly, if not exclusively, indoors.

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
[18]reported 0.1 percent of Covid-19 cases were traced to outdoor
transmission.)

Image
[06tufekci-outside-articleLarge.jpg?quality=75&auto=webp&disabl
e=upscale]
Credit...Tomasz Lazar

The omission is not surprising. Throughout the pandemic, the W.H.O. was
slow to accept the key role that infectious particles small enough to
float could be playing.

Mary-Louise McLaws, an epidemiologist at the University of New South
Wales in Sydney, Australia, and a member of the W.H.O. committees that
craft infection prevention and control guidance, wanted all this
examined but knew the stakes made it harder to overcome the resistance.
She told [19]The Times last year, “If we started revisiting airflow, we
would have to be prepared to change a lot of what we do.” She said it
was a very good idea, but she added, “It will cause an enormous shudder
through the infection control society.”

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 C.D.C. didn’t recommend masks at first. Why bother if
one can simply stay out of their range? After the C.D.C.
[20]recommended masks in April 2020, the W.H.O. [21]shifted last June,
but it first suggested ordinary people generally wear masks if physical
distancing could not be maintained, and [22]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 [23]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 that if ventilation
might not be adequate, masks should be worn indoors, regardless of
distancing.

In contrast, if the aerosols had been considered a major form of
transmission, in addition to distancing and masks, advice would have
centered on ventilation and airflow, as well as time spent indoors.
Small particles can accumulate in enclosed spaces, since they can
remain suspended in the air and travel along air currents. This means
that indoors, three or even six feet, while helpful, is not completely
protective, especially over time.

To see this misunderstanding in action, look at what’s still happening
throughout the world. In India, where hospitals have run out of
supplemental oxygen and people are dying in the streets, money is being
spent on [24]fleets of drones to spray anti-coronavirus disinfectant in
outdoor spaces. Parks, beaches and outdoor areas keep getting
[25]closed around the world. This year and last, organizers
[26]canceled outdoor events for the National Cherry Blossom Festival in
Washington, D.C. Cambodian customs officials advised [27]spraying
disinfectant outside vehicles imported from India. The examples are
many.

Meanwhile, many countries allowed their indoor workplaces to open but
with inadequate aerosol protections. There was no attention to
ventilation, installing air filters as necessary or even opening
windows when possible, more to having people just distancing three or
six feet, sometimes not requiring masks beyond that distance, or
spending money on hard plastic barriers, which may be[28] useless at
best. (Just this week, President Biden [29]visited a school where
students were sitting behind plastic shields.)

This occurred throughout the world in the past year. The United States
has been a bit better, but the C.D.C. did not really accept aerosol
transmission until [30]October, though still relegating it to a
secondary role until its change on Friday, which put the risk infection
from inhaling these tiny particles first on its list of means of
transmission.

*

The scientific wrangling, resistance and controversy that prevented a
change in guidance stem from a century of mistaken assumptions whose
roots go back to the origins of germ theory of disease in the 19th
century.

Until germ theory became established in the 19th century, many people
believed that deadly diseases like cholera were caused by miasma —
stinking fumes from organic or rotting material. It wasn’t easy to
persuade people that creatures so small that they could not be seen in
a seemingly innocent glass of water could be claiming so many lives.

This was a high-stakes fight: Getting the transmission mechanisms of a
disease wrong can lead to mitigations that not only are ineffective but
also make things worse. During the 19th century, fearing miasma,
Londoners worked hard to direct their stinky sewers into the nearby
Thames River, essentially spreading cholera even more.

But clear evidence doesn’t easily overturn tradition or overcome
entrenched feelings and egos. John Snow, often credited as the first
scientific epidemiologist, showed that a contaminated well was
responsible for a 1854 London cholera epidemic by removing the
suspected pump’s handle and documenting how the cases plummeted
afterward. Many other scientists and officials wouldn’t believe him for
12 years, when the link to a water source showed up again and became
harder to deny. (He died years earlier.)

Similarly, when the Hungarian physician Ignaz Semmelweis realized the
importance of washing hands to protect patients, he lost his job and
was widely condemned [31]by disbelieving colleagues. He wasn’t always
the most tactful communicator, and his colleagues [32]resented his
brash implication that they were harming their patients (even though
they were). These doctors continued to kill their patients through
cross-contamination for decades, despite clear evidence showing how
death rates had plummeted in the few wards where midwives and Dr.
Semmelweis had succeeded in introducing routine hand hygiene. He
ultimately died of an [33]infected wound.

Disentangling causation is difficult, too, because of confusing
correlations and conflations. Terrible smells frequently overlap with
unsanitary conditions that can contribute to ill health, and in
mid-19th-century London, death rates from cholera were higher in parts
of the city with poor living conditions.

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 [34]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.

In modern medical parlance, respiratory transmission routes are divided
between the larger droplets, associated with diseases that spread at
close distance, and the smaller aerosols (sometimes also called droplet
nuclei), associated with diseases like measles that we know can spread
at long distance and are usually highly contagious. Indeed, studies
showing that respiratory diseases spread more easily in proximity to
infected people seemingly confirmed the role of droplets.

It was in this context in early 2020 that the W.H.O. and the C.D.C.
asserted that SARS-CoV-2 was transmitted primarily via these heavier,
short-range droplets, and provided guidance accordingly.

But from the beginning, the way the disease was spreading around the
world did not fit this theory well. In February 2020, after an infected
person was found to have boarded the cruise ship [35]Diamond Princess,
hundreds of people trapped on board for weeks were infected, including
[36]567 of the 2,666 passengers, who were largely confined to their
rooms and delivered food by masked personnel — [37]hard to explain
solely with droplet-driven transmission. (Hitoshi Oshitani, a Japanese
virologist who played an important role in his country’s response to
the epidemic, said it was this ship outbreak that helped [38]convince
him this was airborne — and it’s why Japan planned around airborne
transmission assumptions from [39]as early as February 2020.)

Then there were the many superspreader events around the world that
defied droplet explanations. In March 2020 [40]in Mount Vernon, Wash.,
61 pandemic-aware people [41]showed up to a choir practice and sang
with some distance between them in a large space, were provided hand
sanitizer and left the doors open, reducing the need for people to
touch the handles. But [42]53 of them were confirmed or strongly
suspected to have contracted Covid-19 anyway, and two died.
Long-distance transmission was being documented as well: One [43]study
from China in April 2020, clearly documenting transmission from beyond
one meter, had video evidence showing the initially infected person had
not come very close to those he infected, and there were no common
surfaces touched.

Epidemiological studies and examples kept pouring in, too, all of them
showing that Covid-19 was spreading primarily indoors and clusters were
concentrated in poorly ventilated spaces. And when outdoor transmission
did occur, it was often when people were in prolonged close contact,
talking or yelling, as with construction workers on the same site.

The disease was also greatly overdispersed, sometimes being not very
contagious and other times dramatically so. Large-scale studies showed
that more than 70 percent of infected people did not transmit to any
other person, while as few as 5 percent may be responsible for 80
percent of transmissions through [44]superspreading events. Despite
databases documenting thousands of indoor superspreader incidents, I’m
not aware of a single confirmed outdoor-only case of superspreading.

None of this could be explained easily if the disease were “primarily
transmitted between people through respiratory droplets and contact
routes,” as the W.H.O. [45]had said, since those larger, heavier
particles would behave the same indoors as outdoors, would be largely
indifferent to ventilation and would not be conducive to so much
superspreading.

Finally, it was clear from early on that people who weren’t yet sick or
coughing or sneezing — which produce a lot more droplets — were
transmitting and that things correlated with aerosol emissions like
talking, yelling and singing were associated with many of the
outbreaks.

Amid the growing evidence, in July, hundreds of scientists [46]signed
an open letter urging the public health agencies, especially the
W.H.O., to address airborne transmission of the coronavirus.

Image
Credit...Tomasz Lazar

That month, after the open letter, the W.H.O. [47]updated its guidance
to say that “short-range aerosol transmission” from infected people in
poorly ventilated spaces over time “cannot be ruled out” but went on to
say that “the detailed investigations of these clusters suggest that
droplet and fomite transmission could also explain human-to-human
transmission within these clusters” and that close contact could still
be the reason, “especially if hand hygiene was not performed and masks
were not used when physical distancing was not maintained.”

Evidence kept accumulating. Transmission was documented in [48]adjacent
rooms in a quarantine hotel where people never interacted. Several
hospital workers [49]were [50]proved to have been infected despite
strict contact and droplet precautions. Viable virus was found in
[51]air samples from [52]hospital [53]rooms of Covid-19 patients who
hadn’t had aerosol-generating procedures and in an [54]air sample from
an infected person’s car. The virus was found in [55]exhaust vents in
hospitals, and [56]ferrets in cages connected only via shared air
infected each other. And so on.

There were quibbles with each study: Was the sampled virus infective
enough? (It is hard to catch the viruses from the air without
destroying them.) Could some fomite connection have been missed? Still,
it kept getting harder to deny the role of aerosols as a major factor.

Last October, the C.D.C. [57]published updated guidance acknowledging
airborne transmission, but as a secondary route under some
circumstances, until it acknowledged airborne transmission as crucial
on Friday. And the W.H.O. kept inching forward in its public
statements, most recently a week ago.

*

[58]Linsey Marr, a professor of engineering at Virginia Tech who made
important contributions to our understanding of airborne virus
transmission before the pandemic, pointed to two key scientific errors
— rooted in a lot of history — that explain the resistance, and also
opened a fascinating sociological window into how science can get it
wrong and why.

First, Dr. Marr said, the upper limit for particles to be able to float
is actually 100 microns, not five microns, as generally thought. The
incorrect five-micron claim may have [59]come about because earlier
scientists conflated the size at which respiratory particles could
reach the lower respiratory tract (important for studying tuberculosis)
with the size at which they remain suspended in the air.

Dr. Marr said that if you inhale a particle from the air, it’s an
aerosol. She agreed that droplet transmission by a larger respiratory
particle is possible, if it lands on the eye, for example, but
biomechanically, she said, nasal transmission faces obstacles, since
nostrils point downward and the physics of particles that large makes
it difficult for them to move up the nose. And in lab measurements,
people emit far more of the easier-to-inhale aerosols than the
droplets, she said, and even the smallest particles can be virus laden,
sometimes more so than the larger ones, seemingly because of how and
where they are produced in the respiratory tract.

Second, she said, proximity is conducive to transmission of aerosols as
well because aerosols are more concentrated near the person emitting
them. In a twist of history, modern scientists have been acting like
those who equated stinky air with disease, by equating close contact, a
measure of distance, only with the larger droplets, a mechanism of
transmission, without examination.

Since aerosols also infect at close range, measures to prevent droplet
transmission — masks and distancing — can help dampen transmission for
airborne diseases as well. However, this oversight led medical people
to circularly assume that if such measures worked at all, droplets must
have played a big role in their transmission.

Other incorrect assumptions thrived. For example, in July, right after
the letter by the hundreds of scientists challenging the droplet
paradigm, [60]Reuters reported that Dr. John Conly, who chairs a key
W.H.O. infection prevention working group, said that there would be
many more cases if the virus was airborne and asked, “Would we not be
seeing, like, literally billions of cases globally?” He made similar
claims last month. And he is not the only member of that group to
assert this, a common assumption in the world of infection control
[61]well into 2021.

However, Dr. Marr pointed out, there are airborne diseases, like
measles, that are highly contagious and others, like tuberculosis, that
are not. Moreover, while SARS-CoV-2 is certainly not as infectious as
measles on average, it can be highly infectious in the superspreading
events driving the pandemic.

Many respiratory viruses carried by aerosols survive better in colder
environments and lower relative humidity, Dr. Marr said, again fitting
the pattern of outbreaks around the world, for example, in many
meatpacking plants. Plus, some activities produce more aerosols —
talking, yelling, singing, exercising — also fitting the pattern of
outbreaks globally.

Why did it take so long to understand all this?

*

One reason is that our institutions weren’t necessarily set up to deal
with what we faced. For example, the W.H.O.’s [62]Infection Prevention
and Control (I.P.C.) global unit primarily concentrates on health care
facilities. Many of the experts they enlisted to form the Covid-19
I.P.C. Guidance Development Group were hospital-focused, and some of
them specialized in antibiotic-resistant bacterial infections that can
spread wildly in health care facilities when medical personnel fail to
regularly wash their hands. So this focus made sense in a prepandemic
world. Hospitals employ trained health care workers and are fairly
controlled, well-defined settings, with different considerations from
those of a pandemic across many environments in the real world.
Further, in some countries like the United States, they tend to have
extensive engineering controls to dampen infections, involving
aggressive air-exchange standards, almost like being outdoors. This is
the opposite of modern office and even residential buildings, which
tend to be more sealed for energy efficiency. In such a medical
environment, hand hygiene is a more important consideration, since
ventilation is taken care of.

Another dynamic we’ve seen is something that is not unheard-of in the
history of science: setting a higher standard of proof for theories
that challenge conventional wisdom than for those that support it.

As part of its assessment of the virus’s spread, the W.H.O. asked a
group of scientists last fall to [63]review the evidence on
transmission of the coronavirus. When reviewing airborne transmission,
the group focused mostly on studies of air samples, especially if live
virus was captured from the air, which, as mentioned above, is
extremely hard. By that criterion, airborne transmission of the measles
virus, which is undisputed, would not be accepted because no one has
cultivated that pathogen from room air. That’s also true of
[64]tuberculosis. And while scientists, despite the difficulties, had
managed to capture viable SARS-CoV-2 in three studies that I’m aware
of, the review noted that the virus was detected only intermittently in
general, disputed whether the captured live virus was infective enough
and ultimately said it could not reach “firm conclusions over airborne
transmission.” The lead author and another senior member of the
research group previously said they believed transmission was driven by
droplets.

The skepticism about airborne transmission is at odds with the
acceptance of droplet transmission. Dr. Marr and [65]Joseph Allen, the
director of the Healthy Buildings program and an associate professor at
Harvard’s T.H. Chan School of Public Health, told me that droplet
transmission has never been directly demonstrated. Since Dr. Chapin,
close-distance transmission has been seen as proof of droplets unless
disproved through much effort, as was finally done for tuberculosis.

Another key problem is that, understandably, we find it harder to walk
things back. It is easier to keep adding exceptions and justifications
to a belief than to admit that a challenger has a better explanation.

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.

In a contemporary example of this attitude, the initial public health
[66]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 [67]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 [68]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 [69]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.

Galileo is said to have murmured, “And yet it moves,” after he was
forced to recant his theory that the earth moved around the sun.
Scientists who studied bioaerosols could only say, “And yet it floats.”

*

So much of what we have done throughout the pandemic — the excessive
hygiene theater and the failure to integrate ventilation and filters
into our basic advice — has greatly hampered our response. Some of it,
like the way we underused or even shut down outdoor space, isn’t that
different from the 19th-century Londoners who flushed the source of
their foul air into the Thames and made the cholera epidemic worse.

Image
Credit...Tomasz Lazar

Righting this ship cannot be a quiet process — updating a web page
here, saying the right thing there. The proclamations that we now know
are wrong were so persistent and so loud for so long.

It’s true that as the evidence piled on, there was genuine progress and
improvement, especially as of late. Even before the change in language
last week, for example, the W.H.O. published helpful guides on
ventilation, first in [70]July and [71]updating it in March. Recently,
though the organization’s documents have lagged, more of its officials
have started giving advice compatible with aerosol transmission,
emphasizing things like close mask fit — which matters little for
droplet transmission — and ventilation — which matters even less. All
this is good, but nowhere near enough to change the regulations and
policy bundles that had already been put in place around the world.

And the progress we’ve made might lead to an overhaul in our
understanding of many other transmissible respiratory diseases that
take a terrible toll around the world each year and could easily cause
other pandemics.

So big proclamations require probably even bigger proclamations to
correct, or the information void, unnecessary fears and misinformation
will persist, damaging the W.H.O. now and in the future.

Scientists have responded. In just the past few weeks, there has been a
flood of articles published about airborne transmission in leading
medical journals. Dr. Marr and other scientists told me the situation
was very difficult until recently, as the droplet dogma reigned. I
co-wrote one of those papers, published in [72]The Lancet last month,
arguing that aerosols may be the predominant mode of transmission for
SARS-CoV-2, a step farther.

I’ve seen [73]our paper used in India to try to reason through aerosol
transmission and the necessary mitigations. I’ve heard of people in
India closing their windows after hearing that the virus is airborne,
likely because they were not being told how to respond. Plus, there are
important questions for what this means for higher-risk settings, like
medical facilities.

The W.H.O. needs to address these fears and concerns, treating it as a
matter of profound change, so other public health agencies and
governments, as well as ordinary people, can better adjust.

The past year has revealed how crucial the agency is, despite being
hampered by chronic underfunding, lack of independence and attempts to
turn it into a political football by big powers. Like other public
health organizations, many of its dedicated staff members work
tirelessly under difficult conditions to safeguard health around the
world. Maintaining its credibility is essential not just for the rest
of this terrible pandemic but in the future.

It needs to begin a campaign proportional to the importance of all
this, announcing, “We’ve learned more, and here’s what’s changed, and
here’s how we can make sure everyone understands how important this
is.” That’s what credible leadership looks like. Otherwise, if a web
page is updated in the forest without the requisite fanfare, how will
it matter?

Confused about when to wear a mask?
__________________________________________________________________

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