Canceling large public gatherings. Asking students to stay home from school. Closing down borders.
Many places around the world have already implemented such drastic steps in response to the new coronavirus outbreak that originated in China and has spread to at least 27 territories outside mainland China. If the U.S., which has 11 cases so far, begins to see sustained human-to-human transmission, health officials may also have to rapidly step up their own use of “social distancing” measures to prevent further spread.
Just last week, the U.S. reported its first case of human-to-human transmission, where an Illinois woman in her 60s who had traveled to Wuhan passed on the virus to her husband, who hadn’t traveled with her. And late Sunday night, officials in California reported another such case. A 57-year-old man recently returned from China, and he and his wife — who did not travel to China — are now both sick with the virus.
Public health officials there were quick to point out that the threat to the U.S. still remains low. “The virus is not spreading widely across the community at this time,” Dr. Ngozi Ezike, director of the Illinois Department of Public Health, told reporters last week, adding, “We are not recommending people in the general public take additional precautions such as canceling activities or avoiding going out of their homes.”
But officials there and elsewhere in the U.S. are already thinking ahead for when they may have to put into place larger directives in communities to stop the spread of the virus, especially as the nature of the outbreak — which has infected more than 17,000 people and killed more than 360 — is changing rapidly.
Already, federal health officials took the rare step late last week of quarantining all 195 American citizens evacuated from Wuhan, China, where the outbreak is believed to have originated.
Dr. Nancy Messonnier, director of the Center for Disease Control and Prevention’s National Center for Immunization and Respiratory Diseases, said the agency is “preparing as if this is the next pandemic,” meaning the worldwide spread of a disease.
“If we take strong measures now, we may be able to blunt the impact of the virus on the United States,” she said.
Late Friday, the federal government also declared a national public health emergency and issued a ban on foreign nationals traveling to the U.S. from China. Other social distancing steps the U.S. has already been taking include airport screenings in 20 different cities and isolating sick patients, which the U.S. has employed on a smaller scale.
“Isolating someone who is sick is very standard practice,” said Dr. Ashish Jha, a public health researcher at the Harvard T.H. Chan School of Public Health.
As long as the health system can keep on top of emerging cases, there isn’t a need to think about implementing larger measures, he said. But if the infections pop up much faster than officials can track them, or if there are signs that health care systems might get overwhelmed, then it might be time to call in reinforcement measures, he said.
No single measure is perfect, and choosing which to implement — and when — is highly subjective. “These decisions basically are an art form, not a science,” said Dr. Julie Gerberding, who served as CDC director under President George W. Bush.
As a new outbreak unfolds, officials are simultaneously learning about the virus and its transmission, she explained, adding, “and making decisions about when you should and must intervene is really hard to do in real time.”
“The way we always thought about it at the [CDC] is like Swiss cheese,” Gerberding, who is now chief patient officer at Merck, said. “Each individual slice has a lot of holes but if you stack up a number of them, then you have a pretty good barrier.”
One recent emergency that experts are likely looking to is the Ebola outbreak in West Africa from 2014-2016. “It was never a huge threat in the U.S., but it caused a huge panic,” said Polly Price, a global health law expert at Emory University in Atlanta. U.S. officials in Dallas, where the first U.S. case of the disease was detected, debated various social distancing measures. Immediate family members of the patient and the two nurses who took care of him were quarantined in their homes, but larger measures, including shutting down transit and school closures, were proposed but never ordered. “They worked through that nicely,” Price said.
Despite the fluid nature of how social distancing measures are put into place, there are a few signs that officials look out for. The main one is sustained community transmission, Jha said, in which the rate of new infections is exceeding what any hospital or town can handle.
There are other tells: “Children are often also the canary in the coal mine when flu is going to arrive in the community,” Gerberding said. And given that the new coronavirus causes respiratory illness, lessons learned from handling flu outbreaks could be applied here as well. “Social distancing usually starts with consideration of schools and day care because we know that’s where a large proportion of viruses are transmitted on a [regular] basis from one child to another.”
Beyond school closures, health agencies may also recommend that employers encourage their workers to telecommute.
“Some people have the choice to telecommute, others don’t,” said Dr. Nicole Lurie, who served as the assistant secretary for preparedness and response at the Department of Health and Human Services during the Obama administration. “Some people also have a choice about how they get to work whereas others will have to take transit. It’s really about keeping people more apart from another and avoiding really crowded spaces.”
There isn’t very robust data to suggest that social distancing is effective, which can complicate decisions about which measures to put into place.
“We haven’t had a whole lot of mass cancellation events, and it’s hard to know what would have happened if you hadn’t put measures into place,” Jha said.
A step like quarantining can also be disruptive. “One of the big problems with large-scale quarantining is that they are incredibly costly,” said Nicholas Evans, a bioethicist at the University of Massachusetts in Lowell, because trade, travel, and other functions of our globalized world are interrupted. “We could look at another major recession if people overreact to this outbreak, and that’ll hurt a lot more people in the long run than this disease might.”
Moreover, Evans said that quarantine measures could lead to more cases of infection: “You’re essentially locking someone up with someone else with the disease.” During the 2003 SARS outbreak, Canadian officials in Toronto quarantined 100 people for every case of SARS — a CDC analysis later found that the maximum number of people who should have been quarantined per SARS case was four.
And previous lessons, like from the H1N1 flu pandemic in 2009, suggest that travel bans like the one the U.S. just implemented are ineffective. In one study, researchers modeled the likelihood that restrictions on travel to Mexico actually made a difference in containing the flu virus. The restrictions didn’t work to contain the virus, and the authors conclude that “it is unlikely that given the ever-increasing mobility of people travel restrictions could be used effectively in a future pandemic event.”
There are still bigger costs to more large-scale public health interventions like shutting down schools, according to Jha. Those costs: a sense of panic and heightened concern. China’s extreme quarantining has already been questioned and other similar measures are likely to similarly spark controversy. “I hope there will be data available to see if [they] worked,” Lurie, who now serves as a consultant to the Coalition for Epidemic Preparedness Innovations, said.
The key, experts say, is to keep the public informed and to be transparent about why certain measures are being implemented.
“An integral part of any public health response has to be accurate and frequent communication,” said Dr. Oxiris Barbot, New York City’s public health commissioner. “Fear and misinformation can be more harmful than the virus we are fighting against — it’s important to focus on the facts about the virus and the risk [to the public],” she said.
As U.S. health officials learn more about the virus, they are likely to update their guidelines for what health care providers ought to look for in patients who possibly have the disease. Agencies will also be updating the general public as far as what symptoms they may need to look out for and what precautions they’ll have to take.
“This is going to be a very dynamic situation,” Lurie said. “It is likely that different communities will experience the outbreak at different times, and with different intensities.”