An outbreak of a never-before-seen coronavirus that causes viral pneumonia has continued to surge in China, with over 4,500 confirmed cases and over 100 deaths.
Nearly all of the cases and all of the deaths are reported from China. But there have been small numbers of cases in travelers to other countries, including Australia, Cambodia, Canada, France, Germany, Japan, Malaysia, Nepal, Singapore, Sri Lanka, Taiwan, Thailand, the Republic of Korea, the United States, and Vietnam.
Five travel-related cases have been confirmed in the United States, according to officials at the Centers for Disease Control and Prevention. Arizona, Washington, and Illinois have each reported one case, and California has reported two cases. All of the cases had connections to Wuhan, the capital city of the central Hubei province where the outbreak erupted.
The CDC said in a press conference Monday, January 27, that there are 105 other people in 26 states who have been identified as having possible travel exposure to the virus. Of those 105, 32 have already tested negative for the virus. Results for the remaining 73 people are pending.
At this time, the public health risk from this virus to the American public is low, Dr. Nancy Messonnier told reporters Monday. Dr. Messonnier is the director of the CDC’s National Center for Immunization and Respiratory Diseases.
Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, put things more bluntly. In a radio interview Sunday, he said:
“The American people should not be worried or frightened by this. It’s a very, very low risk to the United States.”
What we know about the virus so far
The virus—which is being referred to as the 2019 novel coronavirus, or 2019-nCoV—is a member of the large coronavirus family. Coronaviruses, named for the crown-like halo of spikes on their outer surfaces, cause a wide range of respiratory and gastrointestinal infections in humans and animals. Several strains of coronavirus already circulate in people, causing common, mild-to-moderate upper-respiratory-tract infections (common colds). Other family members largely circulate in animals, such as bats.
In several instances, coronaviruses have jumped from animal species to humans, which can occur when wild animals and people are in close, unhygienic conditions. Species jumps can result in severe disease in people. Such is the case for the coronaviruses that cause SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome). SARS was linked to viruses in bats, masked palm civets, and raccoon dogs, and MERS was linked to viruses in bats and dromedary camels.
Like SARS and MERS, 2019-nCoV is suspected to have jumped from animals to people in Wuhan. The outbreak was initially linked to a live animal market in the city, which contained a range of animals, including chickens, bats, marmots, snakes, and other wild animals. A majority of the early cases has direct exposure or a link to the market. In fact, early reports found that many of the cases were in people who worked at the market.
However, a new report published in The Lancet describing 41 early cases in the outbreak indicate that the earliest identified person sickened had no epidemiological links to the market. The case was in a man who had a laboratory-confirmed 2019-nCoV infection with onset of symptoms on December 1, 2019. None of the man’s family became ill and, intriguingly, he had no identifiable ties to any of the other cases in the outbreak. The significance of this and the ultimate source of the outbreak remain unknown.
Investigations into the origins of SARS and MERS have determined that bats seem to be a source (aka a reservoir) for different coronaviruses. But again, no animal source has yet been confirmed for this new coronavirus strain. (There have been reports claiming that the virus came from snakes, but experts are skeptical of the suggestion.)
What we know about the infections so far
In people, the virus appears to be able to cause asymptomatic cases, as well as illnesses that range from mild respiratory infections to life-threatening pneumonia and respiratory distress, according to preliminary clinical data.
The incubation period—the time between an exposure and the onset of symptoms—appears to be between two and 14 days. Common symptoms are fever, cough, chest tightness, and trouble breathing.
The mortality rate is estimated to be around 3 percent, and the rate of severe illness has hovered around 20 percent. But both of those calculations may easily change as the outbreak continues, more testing is performed, and any additional mild cases are detected.
The majority of cases so far are in older adults, mainly men and many with underlying health conditions that make them more susceptible to disease. But there are reports of cases in healthy people, as well as children and infants. The youngest confirmed case has been reported to be in a nine-month-old girl in Beijing.
There have also been reports of asymptomatic cases in several places. For instance, in a second case report published in The Lancet, researchers identified an asymptomatic case in a 10-year-old boy. The case was discovered in a cluster of infections in a family. The boy’s asymptomatic case was only caught at his parent’s insistence that he be examined and tested. Both of the boy’s parents and three of his grandparents had contracted the virus after the family traveled to Wuhan and visited other sick relatives in a local hospital.
The discovery of asymptomatic cases has led to concerns that infected people with no symptoms may be unknowingly spreading the virus and thwarting outbreak control efforts, such as quarantines. However, it’s unclear if this is happening, and experts suspect that if it is, it may only be a limited source of new infections.
What we know about transmission so far
So far, experts suspect that 2019-nCoV mainly spreads through respiratory droplets—sprayed from things like coughs and sneezes—that can then enter the nose, mouth, or eyes of an uninfected individual to cause an infection. It’s still unclear when during an incubation period an infected person is contagious, though.
The virus appears to mainly be spreading among people who have close contact with each other, such as between family members and from patients to medical staff, and not, say, strangers passing in an airport.
This is a positive sign in terms of outbreak control, as the NIH’s Anthony Fauci described:
It does not seem to be as efficient in the persistent sustained transmission from human to human… without a doubt it can spread from one human to another. What it doesn’t seem yet to be doing as efficiently—certainly not like influenza, which spreads very efficiently in a sustained way—this does not do so. Which means that, just like SARS, we have the possibility—with good public health measures—of hopefully getting control of it.
Can face masks protect someone from being infected?
Not completely. Surgical masks, which many people are using to try to protect themselves, may help to keep an uninfected person from inhaling infectious droplets and may help to keep an infected person from spreading the infection. But masks are far from foolproof. The virus can still enter the nose, eyes, or openings around the mask, particularly if it is not on properly or tightly.
The R0 question
There’s been a lot of discussion and speculation online about the 2019-nCoV outbreak’s R0 (pronounced R-naught), the so-called basic reproduction number of an infectious agent. An R0 is a complex calculation meant to represent the average number of new infections generated by any one infected person in a completely susceptible population. Generally, an R0 of 1 or less indicates that an outbreak will peter out; values greater than 1 suggest that the outbreak will continue. These numeric values are sometimes used as a shorthand for an infectious agent’s infectiousness, but they are often misrepresented and misinterpreted.
For one thing, it’s important to keep in mind that R0 is not an intrinsic property of an infectious agent. It’s a descriptive calculation of an outbreak that can change with changing circumstances and control measures, such as viral mutations or effective quarantines.
There are already many different, preliminary estimates of 2019-nCoV outbreak’s R0. The World Health Organization has reported a preliminary estimate of R0 as 1.4 to 2.5. For a point of reference, the highly infectious measles virus has an R0 of 12 to 18.
The R0 estimates are extremely preliminary and likely to change continually during the outbreak and as new control measures are put into place.
Words of caution
Whenever novel viruses jump to new hosts (in this case, people), there’s the potential that the virus can continue to mutate and adapt to it new victims. Coronaviruses are notorious for mutating and recombining. For humans, this could mean that infections might become more or less severe, or it could mean that transmission from one person to another might become easier.
This volatility—along with all of the other many unknowns in an outbreak of a novel virus—make public health experts particularly anxious. As officials race to get a handle on the situation, the severity of the disease and ease of its spread can change extremely quickly.
The good news so far is that 2019-nCoV does not seem to be mutating much. Researchers swiftly examined the full genetic sequences of many 2019-nCoV samples isolated during the outbreak at different time points and places. So far, the genetic data suggests that the virus recently jumped to humans—meaning that the outbreak was caught promptly—and that it is not undergoing speedy genetic changes.
Of course, this situation could still change—and change quickly—at any point as the outbreak continues.
So what are officials doing to stop 2019-nCoV?
Officials in China have issued travel bans and restrictions, cancelling hundreds of flights and freezing public transportation, though it’s unclear if this will work to contain the virus. On Sunday, January 26, the mayor of Wuhan reported that 5 million residents left the city before the lockdown began. Around 9 million people reportedly remain in the city.
Hong Kong announced Tuesday, January 28 that it will implement broad travel restrictions from mainland China.
In the US, the CDC advises all travelers to avoid all non-essential travel to China. Health officials are also stepping up health screening of patients from China, with screening to take place in 20 airports around the country.
The CDC is also working to optimize a genetic-based diagnostic test for 2019-nCoV cases. Currently, testing is being done in CDC labs, which takes about four to six hours once the CDC gets hold of a patient’s samples (typically respiratory sample and blood).
The NIH’s Fauci said in a press conference Tuesday, January 28, that the NIH is working on faster, point-of-care diagnostics and therapeutics, as well as a messenger-RNA-based vaccine. “I anticipate, with some cautious optimism, that we will be in a phase-I trial [of that experimental vaccine] within the next three months,” Fauci said.
Officials at the World Health Organization are currently consulting with leaders in China about outbreak management.
“Stopping the spread of this virus both in China and globally is WHO’s highest priority,” WHO Director-General Tedros Adhanom Ghebreyesu said in a statement Tuesday. He continued:
We appreciate the seriousness with which China is taking this outbreak, especially the commitment from top leadership, and the transparency they have demonstrated, including sharing data and genetic sequence of the virus. WHO is working closely with the government on measures to understand the virus and limit transmission. WHO will keep working side-by-side with China and all other countries to protect health and keep people safe.
What should you do?
Don’t panic. The risk to the general public in the United States is low. And risk only increases with exposure, which at the moment means links to people who have recently traveled to outbreak areas of China—people who are already being screened and monitored.
So far, no transmission of the virus has occurred on US soil, though CDC experts expect that it will occur at some point.
On Tuesday, Germany and Japan reported limited transmission of the virus in their countries. For instance, in Germany, a Bavarian man fell ill after contact with a Chinese woman who was diagnosed after returning home. But the health ministry appeared confident that it could keep the virus under control.
“It was to be expected that the virus would come to Germany,” Jens Spahn, Germany’s health minister, said in a statement on Tuesday reported by The New York Times. “But the Bavarian case shows us that we are well prepared.”
The US CDC has shown similar confidence.
It’s also important to keep a clear perspective of the risk. As a report in Kaiser Health News noted on Monday, while the unknowns of a new virus can be frightening, there are currently more imminent threats to public health in the US that should be prioritized—namely, the seasonal flu.
Flu activity is currently high in the United States. The CDC estimates that influenza has already infected at least 15 million people, causing at least 140,000 hospitalizations and at least 8,200 deaths—that’s just in this season so far and just in the US.
For comparison, the terror-inducing 2002-2003 SARS pandemic—caused by a coronavirus relative of 2019-nCoV—sickened over 8,000 people worldwide, killing 774.
As with any season of upper-respiratory infections, health experts recommend that you get a flu shot, wash your hands thoroughly and frequently, cough and sneeze into the bend of your arm (vampire cough), throw away used tissues promptly, and do not touch your face with an unwashed hand.