Dr. Camilla Rothe’s team was among the first to warn about asymptomatic transmission.
Symptomless transmission makes the coronavirus far harder to fight. But
health officials dismissed the risk for months, pushing misleading and
contradictory claims in the face of mounting evidence.
By Matt Apuzzo, Selam Gebrekidan and David D. Kirkpatrick
June 27, 2020
________________________________________
MUNICH — Dr. Camilla Rothe was about to leave for dinner when the
government laboratory called with the surprising test result. Positive. It was
Jan. 27. She had just discovered Germany’s first case of the new coronavirus.
But the diagnosis made no sense. Her patient, a businessman from a
nearby auto parts company, could have been infected by only one person: a
colleague visiting from China. And that colleague should not have been
contagious.
The visitor had seemed perfectly healthy during her stay in Germany. No
coughing or sneezing, no signs of fatigue or fever during two days of long
meetings. She told colleagues that she had started feeling ill after the flight
back to China. Days later, she tested positive for the coronavirus.
Scientists at the time believed that only people with symptoms could
spread the coronavirus. They assumed it acted like its genetic cousin, SARS.
“People who know much more about coronaviruses than I do were absolutely
sure,” recalled Dr. Rothe, an infectious disease specialist at Munich
University Hospital.
But if the experts were wrong, if the virus could spread from seemingly
healthy carriers or people who had not yet developed symptoms, the
ramifications were potentially catastrophic. Public-awareness campaigns,
airport screening and stay-home-if-you’re sick policies might not stop it. More
aggressive measures might be required — ordering healthy people to wear masks,
for instance, or restricting international travel.
Dr. Rothe and her colleagues were among the first to warn the world. But
even as evidence accumulated from other scientists, leading health officials
expressed unwavering confidence that symptomless spreading was not important.
In the days and weeks to come, politicians, public health officials and
rival academics disparaged or ignored the Munich team. Some actively worked to
undermine the warnings at a crucial moment, as the disease was spreading
unnoticed in French
churches, Italian soccer stadiums and Austrian ski bars. A cruise ship, the
Diamond Princess, would become a deadly harbinger of symptomless spreading.
Interviews with doctors and public health officials in more than a dozen
countries show that for two crucial months — and in the face of mounting
genetic evidence — Western health officials and political leaders played down
or denied the risk of symptomless spreading. Leading health agencies including
the World Health Organization and the European Center for Disease Prevention
and Control provided contradictory and sometimes misleading advice. A crucial
public health discussion devolved into a semantic debate over what to call
infected people without clear symptoms.
The two-month delay was a product of faulty scientific assumptions,
academic rivalries and, perhaps most important, a reluctance to accept that
containing the virus would take drastic measures. The resistance to emerging
evidence was one part of the world’s sluggish response to the virus.
It is impossible to calculate the human toll of that delay, but models
suggest that earlier, aggressive action might have saved tens of thousands of
lives. Countries like Singapore and Australia, which used testing and contact-tracing
and moved swiftly to quarantine seemingly healthy travelers, fared far better
than those that did not.
It is now widely accepted that seemingly healthy people can spread the
virus, though uncertainty remains over how much they have contributed to the
pandemic. Though estimates vary, models using data from
Hong Kong, Singapore and China suggest that 30 to 60 percent of spreading
occurs when people have no symptoms.
“This was, I think, a very simple truth,” Dr. Rothe said. “I was
surprised that it would cause such a storm. I can’t explain it.”
Even now, with more than 9 million cases around the world, and a death
toll approaching 500,000, Covid-19 remains an unsolved riddle. It is too
soon to know whether the worst has passed, or if a second global wave of
infections is about to crash down. But it is clear that an array of countries,
from secretive regimes to overconfident democracies, have fumbled their
response, misjudged the virus and ignored their own emergency plans.
It is also painfully clear that time was a critical commodity in curbing
the virus — and that too much of it was wasted.
‘She Was Not Ill’
On the night of Germany’s first positive test, the virus had seemed far
away. Fewer than 100 fatalities had been reported worldwide. Italy, which would
become Europe’s ground zero, would not record its first cases for another three
days.
A few reports out of China had already suggested the possibility of
symptomless spreading. But nobody had proved it could happen.
That night, Dr. Rothe tapped out an email to a few dozen doctors and
public health officials.
“Infections can actually be transmitted during the incubation period,”
she wrote.
Three more employees from the auto parts company, Webasto, tested
positive the following day. Their symptoms were so mild that, normally, it’s
likely that none would have been flagged for testing, or have thought to stay
at home.
Dr. Rothe decided she had to sound the alarm. Her boss, Dr. Michael
Hoelscher, dashed off an email to The New England Journal of Medicine. “We
believe that this observation is of utmost importance,” he wrote.
Editors responded immediately. How soon could they see the paper?
The next morning, Jan. 30, public health officials interviewed the
Chinese businesswoman by phone. Hospitalized in Shanghai, she explained that
she’d started feeling sick on the flight home. Looking back, maybe she’d had
some mild aches or fatigue, but she had chalked them up to a long day of
travel.
“From her perspective, she was not ill,” said Nadine Schian, a Webasto
spokeswoman who was on the call. “She said, ‘OK, I felt tired. But I’ve been in
Germany a lot of times before and I always have jet lag.’”
When the health officials described the call, Dr. Rothe and Dr.
Hoelscher quickly finished and submitted their article. Dr. Rothe did not talk
to the patient herself but said she relied on the health authority summary.
Within hours, it was online. It
was a modest clinical observation at a key time. Just days earlier, the World
Health Organization had said it needed more information about this very topic.
What the authors did not know, however, was that in a suburb 20 minutes
away, another group of doctors had also been rushing to publish a report.
Neither knew what the other was working on, a seemingly small academic rift
that would have global implications.
Academic Hairsplitting
The second group was made up of officials with the Bavarian health
authority and Germany’s national health agency, known as the Robert Koch
Institute. Inside a suburban office, doctors unfurled mural paper and traced
infection routes using colored pens.
Their team, led by the Bavarian epidemiologist Dr. Merle Böhmer,
submitted an article to The Lancet, another premier medical journal. But the
Munich hospital group had scooped them by three hours. Dr. Böhmer said her
team’s article, which went unpublished as a result, had reached similar
conclusions but worded them slightly differently.
Dr. Rothe had written that patients appeared to be contagious before the
onset of any symptoms. The government team had written that patients appeared
to be contagious before the onset of full symptoms — at a time when symptoms
were so mild that people might not even recognize them.
The Chinese woman, for example, had woken up in the middle of the night
feeling jet-lagged. Wanting to be sharp for her meetings, she took a Chinese
medicine called 999 — containing the equivalent of a Tylenol tablet — and went
back to bed.
Perhaps that had masked a mild fever? Perhaps her jet lag was actually
fatigue? She had reached for a shawl during a meeting. Maybe that was a sign of
chills?
After two lengthy phone calls with the woman, doctors at the Robert Koch
Institute were convinced that she had simply failed to recognize her symptoms.
They wrote to the editor of The New England Journal of Medicine, casting doubt
on Dr. Rothe’s findings.
Editors there decided that the dispute amounted to hairsplitting. If it
took a lengthy interview to identify symptoms, how could anyone be expected to
do it in the real world?
“The question was whether she had something consistent with Covid-19 or
that anyone would have recognized at the time was Covid-19,” said Dr. Eric
Rubin, the journal’s editor.
“The answer seemed to be no.”
The journal did not publish the letter. But that would not be the end of
it.
That weekend, Andreas Zapf, the head of the Bavarian health authority,
called Dr. Hoelscher of the Munich clinic. “Look, the people in Berlin are very
angry about your publication,” Dr. Zapf said, according to Dr. Hoelscher.
He suggested changing the wording of Dr. Rothe’s report and replacing
her name with those of members of the government task force, Dr. Hoelscher
said. He refused.
The health agency would not discuss the phone call.
Until then, Dr. Hoelscher said, their report had seemed straightforward.
Now it was clear: “Politically, this was a major, major issue.”
‘A Complete Tsunami’
On Monday, Feb. 3, the journal Science published an article calling Dr.
Rothe’s report “flawed.” Science reported that the Robert Koch Institute had
written to the New England Journal to dispute her findings and correct an
error.
The Robert Koch Institute declined repeated interview requests over
several weeks and did not answer written questions.
Dr. Rothe’s report quickly became a symbol of rushed research.
Scientists said she should have talked to the Chinese patient herself before
publishing, and that the omission had undermined her team’s work. On Twitter,
she and her colleagues were disparaged by scientists and armchair experts
alike.
“It broke over us like a complete tsunami,” Dr. Hoelscher said.
The controversy also overshadowed another crucial development out of
Munich.
The next morning, Dr. Clemens-Martin Wendtner made a
startling announcement. Dr. Wendtner was overseeing treatment of Munich’s
Covid-19 patients — there were eight now — and had taken swabs from each.
He discovered the virus in the nose and throat at much higher levels,
and far earlier, than had been observed in SARS patients. That meant it
probably could spread before people knew they were sick.
But the Science story drowned that news out. If Dr. Rothe’s paper had
implied that governments might need to do more against Covid-19, the pushback
from the Robert Koch Institute was an implicit defense of the conventional
thinking.
Sweden’s public health agency declared that Dr. Rothe’s report had
contained major errors. The agency’s website said, unequivocally, that “there
is no evidence that people are infectious during the incubation period” — an
assertion that would remain online in some form for months.
French health officials, too, left no room for debate: “A person is
contagious only when symptoms appear,” a
government flyer read. “No symptoms = no risk of being contagious.”
As Dr. Rothe and Dr. Hoelscher reeled from the criticism, Japanese
doctors were preparing to board the Diamond Princess cruise ship. A former
passenger had tested positive for coronavirus.
Yet on the ship, parties continued. The infected passenger had been off
the ship for days, after all. And he hadn’t reported symptoms while onboard.
A Semantic Debate
Immediately after Dr. Rothe’s report, the World Health Organization had
noted that patients might transmit the virus before showing symptoms. But the
organization also underscored a point that it continues to make: Patients with
symptoms are the main drivers of the epidemic.
Once the Science article was published, however, the organization waded
directly into the debate on Dr. Rothe’s work. On Tuesday, Feb. 4, Dr. Sylvie
Briand, the agency’s chief of infectious disease preparedness, tweeted a link
to the Science article, calling Dr. Rothe’s report flawed.
With that tweet, the W.H.O. focused on a semantic distinction that would
cloud discussion for months: Was the patient asymptomatic, meaning she would
never show symptoms? Or pre-symptomatic, meaning she became sick later? Or,
even more confusing, oligo-symptomatic, meaning that she had symptoms so mild
that she didn’t recognize them?
To some doctors, the focus on these arcane distinctions felt like
whistling in the graveyard. A person who feels healthy has no way to know that
she is carrying a virus or is about to become sick. Airport temperature checks
will not catch these people. Neither will asking them about their symptoms or
telling them to stay home when they feel ill.
The W.H.O. later said that the tweet had not been intended as a
criticism.
One group paid little attention to this brewing debate: the Munich-area
doctors working to contain the cluster at the auto parts company. They spoke
daily with potentially sick people, monitoring their symptoms and tracking
their contacts.
“For us, it was pretty soon clear that this disease can be transmitted
before symptoms,” said Dr. Monika Wirth, who tracked contacts in the nearby
county of Fürstenfeldbruck.
Dr. Rothe, though, was shaken. She could not understand why much of the
scientific establishment seemed eager to play down the risk.
“All you need is a pair of eyes,” she said. “You don’t need
rocket-science virology.”
But she remained confident.
“We will be proven right,” she told Dr. Hoelscher.
That night, Dr. Rothe received an email from Dr. Michael Libman, an
infectious-disease specialist in Montreal. He thought that criticism of the
paper amounted to semantics. Her paper had convinced him of something: “The
disease will most likely eventually spread around the world.”
Political Paralysis
On Feb. 4, Britain’s emergency scientific committee met and, while its
experts did not rule out the possibility of symptomless transmission, nobody
put much stock in Dr. Rothe’s paper.
“It was very much a hearsay study,” said Wendy Barclay, a virologist and
member of the committee, known as the Scientific Advisory Group for
Emergencies. “In the absence of real robust epidemiology and tracing, it isn’t
obvious until you see the data.”
The data would soon arrive, and from an unexpected source. Dr. Böhmer,
from the Bavarian health team, received a startling phone call in the second
week of February.
Virologists had discovered a subtle genetic mutation in the infections
of two patients from the Munich cluster. They had crossed paths for the
briefest of moments, one passing a saltshaker to the other in the company
cafeteria, when neither had symptoms. Their shared mutation made it clear that
one had infected the other.
Dr. Böhmer had been skeptical of symptomless spreading. But now, there
was no doubt: “It can only be explained with pre-symptomatic transmission,” Dr.
Böhmer said.
Now it was Dr. Böhmer who sounded the alarm. She said she promptly
shared the finding, and its significance, with the W.H.O. and the European
Center for Disease Prevention and Control.
Neither organization included the discovery in its regular reports.
A week after receiving Dr. Böhmer’s information, European health
officials were still declaring: “We are still unsure whether mild or
asymptomatic cases can transmit the virus.” There was no mention of the genetic
evidence.
W.H.O. officials say the genetic discovery informed their thinking, but
they made no announcement of it. European health officials say the German
information was one early piece of an emerging picture that they were still
piecing together.
The doctors in Munich were increasingly frustrated and confused by the
World Health Organization. First, the group wrongly credited the Chinese
government with alerting the German authorities to the first infection.
Government officials and doctors say the auto parts company itself sounded the
alarm.
Then, the World Health Organization’s emergency director, Dr. Michael
Ryan, said on Feb. 27 that the significance of symptomless spreading was
becoming a myth. And Dr. Maria Van Kerkhove, the organization’s technical lead
on coronavirus response, suggested it was nothing to worry about.
“It’s rare but possible,” she said. “It’s
very rare.”
The agency still maintains that people who cough or sneeze are more
contagious than people who don’t. But there is no scientific consensus on how
significant this difference is or how it affects the spread of virus.
And so, with evidence mounting, the Munich team could not understand how
the W.H.O. could be so sure that symptomless spreading was insignificant.
“At this point, for us it was clear,” said Dr. Wendtner, the senior
doctor overseeing treatment of the Covid-19 patients. “This was a misleading
statement by the W.HO.”
‘If This Is True, We’re in Trouble’
The Munich cluster was not the only warning.
The Chinese health authorities had explicitly cautioned that patients
were contagious before showing symptoms. A Japanese bus driver was infected
while transporting seemingly healthy tourists from Wuhan.
And by the middle of February, 355 people aboard the Diamond Princess
cruise ship had tested positive. About a third of the infected passengers and
staff had no symptoms.
But public health officials saw danger in promoting the risk of silent
spreaders. If quarantining sick people and tracing their contacts could not
reliably contain the disease, governments might abandon those efforts
altogether.
In Sweden and Britain, for example, discussion swirled about enduring
the epidemic until the population obtained “herd immunity.” Public health
officials worried that might lead to overwhelmed hospitals and needless deaths.
Plus, preventing silent spreading required aggressive, widespread
testing that was then impossible for most countries.
“It’s not like we had some easy alternative,” said Dr. Libman, the
Canadian doctor. “The message was basically: ‘If this is true, we’re in
trouble.’”
European health officials say they were reluctant to acknowledge silent
spreading because the evidence was trickling in and the consequences of a false
alarm would have been severe. “These reports are seen everywhere, all over the
world,” said Dr. Josep Jansa, a senior European Union health official.
“Whatever we put out, there’s no way back.”
Looking back, health officials should have said that, yes, symptomless
spreading was happening and they did not understand how prevalent it was, said
Dr. Agoritsa Baka, a senior European Union doctor.
But doing that, she said, would have amounted to an implicit warning to
countries: What you’re doing might not be enough.
‘Stop Buying Masks!’
While public health officials hesitated, some doctors acted. At a
conference in Seattle in mid-February, Jeffrey Shaman, a Columbia University
professor, said his research suggested that
Covid-19’s rapid spread could only be explained if there were infectious
patients with unremarkable symptoms or no symptoms at all.
In the audience that day was Steven Chu, the Nobel-winning physicist and
former U.S. energy secretary. “If left to its own devices, this disease will
spread through the whole population,” he remembers Professor Shaman warning.
Afterward, Dr. Chu began insisting that healthy colleagues at his
Stanford University laboratory wear masks. Doctors in Cambridge, England,
concluded that asymptomatic transmission was a big source of infection and
advised local health workers and patients to wear masks, well before the
British government acknowledged the risk of silent spreaders.
The American authorities, faced with a shortage, actively discouraged
the public from buying masks. “Seriously people — STOP BUYING MASKS!” Surgeon
General Jerome M. Adams tweeted on Feb. 29.
By early March, while the World Health Organization continued pressing
the case that symptom-free transmission was rare, science was breaking in the
other direction.
Researchers in Hong Kong estimated that
44 percent of Covid-19 transmission occurred before symptoms began, an estimate
that was in line with a British study
that put that number as high as 50 percent.
The Hong Kong study concluded that
people became infectious about two days before their illness emerged, with a
peak on their first day of symptoms. By the time patients felt the first
headache or scratch in the throat, they might have been spreading the disease
for days.
In Belgium, doctors saw that math in action, as Covid-19 tore through
nursing homes, killing nearly 5,000 people.
“We thought that by monitoring symptoms and asking sick people to stay
at home, we would be able to manage the spread,” said Steven Van Gucht, the
head of Belgium’s Covid-19 scientific committee. “It came in through people
with hardly any symptoms.”
More than 700 people aboard the Diamond Princess were sickened. Fourteen
died. Researchers estimate
that most of the infection occurred early on, while seemingly healthy
passengers socialized and partied.
Government scientists in Britain concluded
in late April that 5 to 6 percent of symptomless health care workers were
infected and might have been be spreading the virus.
In Munich, Dr. Hoelscher has asked himself many times whether things
would have been different if world leaders had taken the issue seriously
earlier. He compared their response to a rabbit stumbling upon a poisonous
snake.
“We were watching that snake and were somehow paralyzed,” he said.
Acceptance. Or Not.
As the research coalesced in March, European health officials were
convinced.
“OK, this is really a big issue,” Dr. Baka recalled thinking. “It plays
a big role in the transmission.”
By the end of the month, the U.S. Centers for Disease Control announced
it was rethinking its policy on masks. It concluded that up to 25
percent of patients might have no symptoms.
Since then, the C.D.C., governments around the world and, finally, the
World Health Organization have recommended that people wear masks in public.
Still, the W.H.O. is sending confusing signals. Earlier this month, Dr.
Van Kerkhove, the technical lead, repeated that transmission from asymptomatic
patients was “very rare.” After an outcry from doctors, the agency said there
had been a misunderstanding.
“In all honesty, we don’t have a clear picture on this yet,” Dr. Van
Kerkhove said. She said she had been referring to a few studies showing limited
transmission from asymptomatic patients.
Recent internet ads confused the matter even more. A Google search in
mid-June for studies on asymptomatic transmission returned a W.H.O.
advertisement titled: “People With No Symptoms — Rarely Spread Coronavirus.”
Clicking on the link, however, offered a much more nuanced picture:
“Some reports have indicated that people with no symptoms can transmit the
virus. It is not yet known how often it happens.”
After The Times asked about those discrepancies, the organization
removed the advertisements.
Back in Munich, there is little doubt left. Dr. Böhmer, the Bavarian
government doctor, published a study
in The Lancet last month that relied on extensive interviews and genetic
information to methodically track every case in the cluster.
In the months after Dr. Rothe swabbed her first patient, 16 infected
people were identified and caught early. All survived. Aggressive testing and
flawless contact-tracing contained the spread.
Dr. Böhmer’s study found “substantial” transmission from people with no symptoms
or exceptionally mild, nonspecific symptoms.
Dr. Rothe and her colleagues got a footnote.