What is a coronavirus?
Coronaviruses are named for the spikes, which resemble a crown or the sun’s corona, that protrude from their surfaces. They can infect both animals and people, and can cause illnesses of the respiratory tract. The infections can range from the common cold to dangerous conditions like Severe Acute Respiratory Syndrome, or SARS, which sickened thousands of people around the world — and killed nearly 800 — during an outbreak in 2003. Middle East Respiratory Syndrome, or MERS, first reported in Saudi Arabia in 2012, is also caused by a coronavirus.
How dangerous is it?
It is hard to accurately assess the lethality of a new virus, and some scientists said initially that the new virus appeared to be less severe than SARS or MERS
But recent news reports indicate that the Chinese authorities muzzled doctors who were first to recognize the new infection, and they may not have been fully transparent about the number of infections and deaths even after the alarm was raised.
It is also not clear whether cases and deaths in China are being carefully tracked and reported. Diagnostic kits and other health resources have been in short supply in the affected regions.
Scientists don’t know who is most susceptible to the new coronavirus. Does it pose a risk to young healthy people? Or, like seasonal flu, is it primarily a threat to the frail and elderly, and those with underlying health problems?
“Whenever a new virus comes out, it takes a while to learn about it,” said Dr. Julie Vaishampayan, chairwoman of the public health committee of the Infectious Diseases Society of America. Right now, she said, “The information about coronavirus is changing rapidly.”
How is the new coronavirus transmitted?
Most respiratory viruses are transmitted through coughing and sneezing.
Though the Chinese authorities initially played down the likelihood of human-to-human transmission, it has now become clear there is significant and sustained transmission among people.
Chinese scientists have warned that some infected people may transmit the virus to others even before they develop illness or experience any symptoms, although a published report documenting asymptomatic transmission in Germany has been criticized as flawed.
If people with no symptoms at all or mild symptoms unrelated to respiratory illness — like headache or back ache — can transmit the virus, that’s “bad news,” said Dr. William Schaffner, an expert in infectious diseases at Vanderbilt University Medical Center.
When people don’t know they are infected, “they’re up and about, going to work or the gym or to religious services, and breathing on or near other people,” Dr. Schaffner said.
A major concern is that with both SARS and MERS, a few patients inexplicably became “superspreaders” who infected huge numbers of people.
Health care workers are particularly vulnerable. At a hospital in Seoul in 2015, one man with MERS transmitted it to 82 patients.
Where did the new coronavirus outbreak start?
On Jan. 8, The New York Times reported that Chinese researchers had identified a new coronavirus as the pathogen behind a mysterious illness that had sickened 59 people in Wuhan.
The cases were linked to a market that sold live fish, animals and birds. The market was later shut down and disinfected.
Past outbreaks of similar illnesses, including SARS, also are believed to have emerged from live animal markets. The coronavirus that causes MERS is transmitted to humans by camels.
The animal that was the source of the new coronavirus is still not known, and the destruction of the Wuhan meat market has made the question nearly impossible to investigate.
Bats are considered a possible source, because they have evolved to coexist with many viruses, including coronaviruses. But it is very possible the virus was transmitted from bats to an intermediate animal, and then to humans.
What symptoms should I look out for?
Symptoms of this virus include fever, severe cough and difficulty breathing or shortness of breath. The illness causes lung lesions and pneumonia. Milder cases may resemble the flu or a bad cold, making detection difficult.
Patients may exhibit other symptoms, too, such as gastrointestinal problems or diarrhea. The incubation period — the time from exposure to the onset of symptoms — is believed to be anywhere from 10 days to two weeks.
If you have a fever or cough and recently visited China, or spent time with someone who did, see your health care provider. Call first, so they can prepare for your visit and take steps to protect other patients and staff from potential exposure.
Is there a test for the virus? What is the treatment?
There is a diagnostic test that can tell if you are infected. It was developed by the Centers for Disease Control and Prevention, based on genetic information about the virus provided by the Chinese authorities.
Right now, tests are done by the C.D.C. in Atlanta, but the test has been approved by the Food and Drug Administration and will be distributed to state laboratories.
The main treatment for coronavirus is supportive care, including making sure the patient is getting enough oxygen, and using a ventilator to push air into the lungs if necessary, Dr. Vaishampayan said.
Patients should rest and drink plenty of fluids “while the immune system does its job and heals itself,” she said.
No drugs have been approved for any coronavirus diseases, including the new coronavirus, though an antiviral medication called remdesivir appears to be effective in animals and was used to treat a patient in Washington State.
Chinese officials are experimenting with other antiviral drugs to treat the infection.
How long will it take to develop a vaccine?
A coronavirus vaccine is still months away — and perhaps years. While new technology, advancements in genomics and improved global coordination have allowed researchers to move at unprecedented speed, vaccine development remains an expensive and risky process.
With each new outbreak, scientists typically have to start from scratch. After the SARS outbreak in 2003, it took researchers about 20 months to get a vaccine ready for human trials. (The vaccine was never needed, because the disease was eventually contained.)
By the time of the Zika outbreak in 2015, researchers had brought the vaccine development timeline down to six months.
Now, they hope that work from past outbreaks will help cut the timeline further. Scientists at the National Institutes of Health and several companies are working on vaccine candidates.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said a preliminary clinical trial may get off the ground in as little as three months. But researchers would still need to conduct extensive testing to prove a vaccine is safe and effective.
Even under the best circumstances, it could take at least a year — maybe longer — for a vaccine to become available.
Should I wear a surgical mask to protect myself?
If you have a respiratory infection, wearing a mask helps protect the people around you from illness by reducing the risk that you will spread the infection. And wearing a surgical mask may somewhat protect you from infection in a crowd if there is an outbreak.
But, generally, surgical masks are not closefitting enough to filter all the air you are breathing in, and heavy-duty N95 respirators are extremely uncomfortable.
Experts recommend washing your hands frequently throughout the day. Avoid touching your face, and maintain a distance from anyone who is coughing or sneezing.
At the moment, the risk of infection with the new coronavirus in the United States “is way too low for the general public to start wearing a face mask,” said Dr. Peter Rabinowitz, co-director of the University of Washington MetaCenter for Pandemic Preparedness and Global Health Security.
But, he added, “if you have symptoms of a respiratory illness, wearing a mask reduces the risk of infecting others.”
I have a trip planned to China. Should I go?
Probably not. The State Department has warned Americans not to go to China unless it is absolutely essential.
If travelers must go, the C.D.C. urges enhanced precautions: avoiding contact with anyone who is sick, as well as with animals and the markets in which they are sold; and refraining from eating raw or undercooked meats.
Many airlines have canceled flights to China, and many travelers were left in limbo while looking to change or cancel bookings.
What are health authorities doing to contain the virus?
China has taken drastic actions to bar people from leaving affected areas, though 5 million people departed Wuhan alone before the restrictions went into effect.
Residents have been told to wear masks in public to prevent the spread of the disease. Two new hospitals for coronavirus patients are being erected; the first opened on Monday.
Governments around the world have been screening incoming passengers from China for signs of illness, and some have gone further, barring entry to people from China. Russia and Mongolia have closed most of their borders with China. Australia said it would evacuate citizens from Wuhan and quarantine them for 14 days on Christmas Island.
C.D.C. teams are also providing assistance with state health investigations of infections, including contact-tracing, which means making sure anyone who may have been in contact with an infected individual is warned of the exposure and is monitored.
The work will enhance the understanding of the virus and how to prevent its spread. C.D.C. teams have also offered to send public health experts to China to help with the investigation and containment efforts.
Reporting was contributed by Knvul Sheikh and Daniel Victor.