Corona virus major outbreak

By the time New York City confirmed its first case of the coronavirus on March 1, thousands of infections were already silently spreading through the city, a hidden explosion of a disease that many still viewed as a remote threat as the city awaited the first signs of spring.

Hidden outbreaks were also spreading almost completely undetected in Boston, San Francisco, Chicago and Seattle, long before testing showed that each city had a major problem, according to a model of the spread of the disease by researchers at Northeastern University who shared their results with The New York Times.

Even in early February — while the world focused on China — the virus was not only likely to be spreading in multiple American cities, but also seeding blooms of infection elsewhere in the United States, the researchers found.

In five major U.S. cities, as of March 1

there were only 23 confirmed cases of coronavirus.

But according to the Northeastern model, there could have actually been

about 28,000 infections in those cities by then.

Boston

2,300

Seattle

2,300

Chicago

3,300

San Francisco

9,300

New York

10,700

Note: Numbers are median estimates that the Northeastern model calculated for each city. The true number of infections could have been substantially higher or lower than shown here.

By Derek Watkins

As political leaders grappled in February with the question of whether the outbreak would become serious enough to order measures like school closures and remote work, little or no systematic testing for the virus was taking place.

“Meanwhile, in the background, you have this silent chain of transmission of thousands of people,” said Alessandro Vespignani, director of the Network Science Institute at Northeastern University in Boston, who led the research team.

Modeling the spread of a disease is inherently inexact, involving estimates of how often people come in contact and transmit the virus as they travel, work and socialize. The model estimates all infections, including those in people who may experience mild or no symptoms and those that are never detected in testing.

Other disease researchers said the findings of Dr. Vespignani’s team were broadly in line with their own analyses. The research offers the first clear accounting of how far behind the United States was in detecting the virus. And the findings provide a warning of what can recur, the researchers say, if social distancing restrictions are lifted too quickly.

Dr. Robert R. Redfield, the director of the Centers for Disease Control and Prevention, said last week that American health officials had been successful in tracking the first known cases and their contacts in the United States before the outbreak got out of control.

“Through Feb. 27, this country only had 14 cases,” he said during a briefing. “We did that isolation and that contact tracing, and it was very successful. But then, when the virus more exploded, it got beyond the public health capacity.”

ImageDr. Robert R. Redfield, the director of the Centers for Disease Control and Prevention, and Vice President Mike Pence during a news briefing this month.
Credit…Pool photo by Chris Kleponis

But the new estimates of coronavirus infections are vastly higher than those official counts.

By late February, as the world’s attention shifted to a dire outbreak in Italy, those 14 known American cases were a tiny fraction of the thousands of undetected infections that the researchers estimated were spreading from person to person across this country.

And more cases may have been arriving in the United States by the day.

“Knowing the number of flights coming into New York from Italy, it was like watching a horrible train wreck in slow motion,” said Adriana Heguy, director of the Genome Technology Center at New York University’s Grossman School of Medicine.

Dr. Heguy’s team and another at the Icahn School of Medicine at Mount Sinai have found through genetic analysis that the seeds of most infections in New York came from multiple locations in Europe, rather than directly from China.

“We weren’t testing, and if you’re not testing you don’t know,” Dr. Heguy said. The new estimates suggesting that thousands of infections were spreading silently in the first months of the year “don’t seem surprising at all,” she said.

There are other signs that the outbreak was worse at an earlier point than previously known. This week, health officials in Santa Clara County, Calif., announced a newly discovered coronavirus-linked death on Feb. 6, weeks earlier than what had been previously thought to be the first death caused by the virus in the United States.

Some scientists cautioned that the new report’s estimates of an enormous, unseen wave of infections could be too high — even though testing surveillance lagged at the time.

“Even with these corrections, it’s still on the high side — this is higher than I would have expected,” said Dr. Donald Burke, a professor of epidemiology at the University of Pittsburgh Graduate School of Public Health.

Others said that the findings were in line with the fragmentary evidence that had been available until now. Lauren Ancel Meyers, a professor of biology and statistics at the University of Texas at Austin, said that her own risk estimates and most recent projections reveal a grim stealthiness of early coronavirus spread.

“By the time you see a few cases, it’s pretty certain that you already have an outbreak underway,” Dr. Meyers said.

Dr. Vespignani’s approach models the outbreak over time based on what is known about the virus and where it has been detected. It estimates the spread of the disease by simulating the movements of individual people based on where people fly, how they move around, when they go to school and other data. By running the model under various conditions — when schools are closed, say — his team estimates where the virus may have spread undetected.

Unseen carriers of the disease, many of them with mild symptoms or none at all, can still spread the virus. For that reason, by the time leaders in many cities and states took action, it was already too late to slow the initial spread.

A few cities with early outbreaks, notably Seattle, are believed to have avoided enormous growth later by heeding the models available at the time and taking action well ahead of the rest of the country.

“We knew the numbers we saw were just the tip of the iceberg, and that there were much greater numbers below the surface,” Jenny A. Durkan, the mayor of Seattle, said in an interview. “We had to act.”

Image
A highway sign in Seattle on April 15.
Credit…Ruth Fremson/The New York Times
Image
As early as March 14, much of Seattle was quiet as people avoided gathering in normally busy public places, like Pioneer Square.
Credit…Grant Hindsley for The New York Times

City and state officials in New York acted more slowly, waiting until known cases were at a higher level to shut down schools and issue a stay-at-home order. Mayor Bill de Blasio was reluctant to embrace shutdowns until mid-March, citing the impact they would have on vulnerable New Yorkers.

  • Frequently Asked Questions and Advice

    Updated June 22, 2020

    • Is it harder to exercise while wearing a mask?

      commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.

    • I’ve heard about a treatment called dexamethasone. Does it work?

      The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.

    • What is pandemic paid leave?

      The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.

    • Does asymptomatic transmission of Covid-19 happen?

      So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.

    • What’s the risk of catching coronavirus from a surface?

      Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.

    • How does blood type influence coronavirus?

      A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.

    • How many people have lost their jobs due to coronavirus in the U.S.?

      The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.

    • My state is reopening. Is it safe to go out?

      States are reopening bit by bit. This means that more public spaces are available for use and more and more businesses are being allowed to open again. The federal government is largely leaving the decision up to states, and some state leaders are leaving the decision up to local authorities. Even if you aren’t being told to stay at home, it’s still a good idea to limit trips outside and your interaction with other people.

    • What are the symptoms of coronavirus?

      Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.

    • How can I protect myself while flying?

      If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)

    • What should I do if I feel sick?

      If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.


“Even while we learn new things about this virus almost daily, one thing remains consistent: New Yorkers were put at risk by the federal government’s total failure to provide us with adequate testing capability,” said the mayor’s press secretary, Freddi Goldstein.

In mid-February, a month before New York City schools were closed, New York City and San Francisco already had more than 600 people with unidentified infections, and Seattle, Chicago and Boston already had more than 100 people, the findings estimate. By March 1, as New York confirmed its first case, the numbers there may already have surpassed 10,000.

From these primary travel hubs and a few other cities, the model shows, the disease was then spread to other locations in the United States.

Dr. Vespignani said he and his research team warned officials of the silent spread, posting some of their early projections in mid-February. “We were talking to officials here, and it was the same reaction we got in Italy, in the U.K., in Spain,” Dr. Vespignani said. “They told me, ‘OK, that’s happening on your computer, not in reality.’ Look,” he added, “No one’s going to shut down a country based on a model.”

The virus moved under the radar swiftly in February and March, doctors and researchers said, because few cities or states had adequate surveillance systems in place. And testing, if it was being done at all, was haphazard. Emergency rooms were busy preparing for the predicted onslaught and likely missed some early virus-related deaths, and did not have the time or tools to verify infections on the fly, experts said.

It was mid-March before teams at N.Y.U. and Mount Sinai began taking samples for testing in New York. On Thursday, Gov. Andrew M. Cuomo announced results from antibody testing of grocery store shoppers— which researchers warned were preliminary and could change — that suggests one of every five New Yorkers may have been infected.

The new findings from the model produce a range of possible outcomes for when the virus may have infected 10 people in each city. In New York, for example, the model shows that the first 10 infected people could have been walking the streets of the city as early as the last week in January, or as late as the middle of February. From there, the infections in the centers of the outbreak grew exponentially.

Trevor Bedford, an associate professor at the Fred Hutchinson Cancer Research Center and the University of Washington in Seattle, said it became clear in late February that “community transmission” — an infectious outbreak — was probably silently underway in Washington after a single test result came back positive for someone who had no symptoms.

Whatever the precise scale of the initial outbreak, that same dynamic will accelerate once measures to mitigate the spread are relaxed without other public health measures in place, Dr. Burke said. “When you take away social distancing, everything will go right through the roof,” he said.

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