A respiratory illness caused by a new coronavirus has global health authorities on high alert.
Since it was first identified in Wuhan, China, in December, the virus has spread to many other countries, including the U.S., and has sickened thousands of people.
Here's what you need to know about the coronavirus.
What, exactly, is the coronavirus?
Coronaviruses, named for their crownlike shape, are a large family of viruses that are common in many species of animals. There are also several coronaviruses that can infect people, according to the Centers for Disease Control and Prevention (CDC). These strains mostly cause coldlike symptoms but can sometimes progress to more complicated lower respiratory tract illnesses, such as pneumonia or bronchitis.
On rare occasion, animal coronaviruses can evolve and spread among humans, as seen with Middle Eastern respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus (SARS-CoV). The virus at the center of the latest outbreak is being referred to as a novel (new) coronavirus (or 2019-nCoV for short), since it's something that health officials have not seen before.
The cause of the latest outbreak is still under investigation. Health experts suspect that the virus originated from an animal source at a large seafood and animal market in Wuhan and is now spreading from person to person.
What are the symptoms?
Patients with 2019-nCoV have reported mild to severe symptoms of fever, cough and shortness of breath that typically begin two to 14 days after exposure, the CDC reports.
Many patients with severe complications from the virus have pneumonia in both lungs; some have died as a result of the virus. Older adults with weakened immune systems or underlying health conditions may be at increased risk for severe disease, health experts say.
The CDC is asking all those with symptoms and a recent travel history to China to call their health care provider. The agency also has tips for what to do if you become infected with 2019-nCoV.
How is the coronavirus spreading?
Health officials are still trying to better understand how 2019-nCoV is spreading among people. But when person-to-person transmission occurred with MERS and SARS, respiratory droplets from coughs and sneezes were the likely culprit, according to the CDC.
Do I need to be worried?
For the general U.S. population, the answer at this point is no. The risk to individuals is “dependent on exposure,” the CDC says. So unless you have recently taken care of someone with the virus or have recently returned from Wuhan, your chances of infection are low.
That said, health officials are taking the situation seriously and are “closely monitoring” the outbreak. The CDC expects more cases in the U.S. and is working with global, state and local public health partners to respond to the threat.
How is it treated?
There is no specific antiviral treatment for 2019-nCoV, just relief from symptoms.
Is there a coronavirus vaccine?
No. There is no vaccine to prevent 2019-nCoV. Researchers are working on developing antiviral drugs to treat the Wuhan coronavirus, though medication is likely months away, at minimum, from becoming available.
What's the best way to protect myself?
The best way to prevent the spread of 2019-nCoV is to avoid exposure, which is why the CDC recommends that people avoid all nonessential trips to China. Travelers coming to the U.S. from China can expect enhanced health screenings at the airport upon arrival.
Health officials also advise taking everyday steps that can prevent the spread of respiratory viruses. Wash your hands often with soap and water (scrub for at least 20 seconds), and use alcohol-based hand sanitizer when soap is not an option. Avoid touching your eyes, nose and mouth with unwashed hands, and steer clear of other sick people.
Some other advice: Stay home when you are sick, and clean and disinfect frequently touched objects and surfaces. Also, get a flu shot if you haven't already. This will not protect you from the coronavirus, but it will increase your chances of staying healthy this winter.
What about those face masks?
Surgical masks offer some level of protection but only when worn properly. Experts recommend a snug-fitting N95 respirator, which blocks large-particle droplets and most small particles that are transmitted by coughs and sneezes, according to the Food & Drug Administration. These masks are available at most drugstores and home improvement outlets.
CORONAVIRUS UPDATES AS OF JANUARY 30TH, 2020
Wuhan coronavirus cases top 8,000 as countries step up evacuation efforts
Italy is stopping air traffic with China
From CNN's Sharon Braithwaite in London
Italy's Prime Minister Giuseppe Conte announced Thursday that all air traffic to and from China has been stopped in an effort to halt the spread of the coronavirus.
“As far as we know, we are the first country in the European Union to adopt such a precautionary measure,” Conte told reporters in Rome.
The decision comes after Italian authorities confirmed Thursday that two Chinese tourists in Italy were diagnosed with coronavirus. The two patients were in isolation at Rome hospital, health officials said.
Wuhan coronavirus and SARS by the numbers
The Wuhan coronavirus has brought up memories of the severe acute respiratory syndrome (SARS) outbreak in Asia back in the early 2000s.
In China, the number of confirmed cases of the Wuhan coronavirus has already exceeded the number infected by SARS in 2002 and 2003. But so far, the SARS outbreak had a considerably greater fatality rate.
American evacuated from China is under quarantine after trying to leave military base
From CNN's Cheri Mossburg in Los Angeles
An American who flew out of China on a chartered flight tried to leave the Southern California military base where authorities have been monitoring nearly 200 people for coronavirus symptoms, health officials said.
The person, who was not identified, has been ordered to stay in quarantine at the March Air Reserve Base near Riverside, California, until the "entire incubation period or until otherwise cleared," Riverside County Public Health said. The incubation period will be 14 days.
"This action was taken as a result of the unknown risk to the public should someone leave MARB early without undergoing a full health evaluation," the agency said Thursday.
Nearly 200 Americans arrived Wednesday at the military base from Wuhan, the epicenter of the deadly coronavirus outbreak in China, and were asked to stay for at least three days so they can be monitored for coronavirus symptoms.
American Airlines pilots sue to halt US-China flights amid coronavirus epidemic
From Shannon Liao, CNN Business
The Allied Pilots Association, a union representing 15,000 American Airlines pilots, has sued the company to halt the carrier's US-China service, citing "serious, and in many ways still unknown, health threats posed by the coronavirus."
The union asked the court for a temporary and immediate restraining order halting the flights as the virus spreads.
"The safety and well-being of our crews and passengers must always be our highest priority, first, last, and always," said APA President Capt. Eric Ferguson. "Numerous other major carriers that serve China, including British Airways, Air Canada, and Lufthansa, have chosen to suspend service to that country out of an abundance of caution."
World Health Organization declares coronavirus a public health emergency of international concern
The World Health Organization has declared the novel coronavirus outbreak a public health emergency of international concern, after an emergency committee reconvened Thursday in Geneva.
Last week, the organization said the virus did not yet constitute the emergency declaration. But with rising numbers and evidence of person-to-person transmission in a handful of cases outside of China, WHO leadership called the committee back together due to the “potential for a much larger outbreak,” WHO Director-General Tedros Adhanom Ghebreyesus told reporters earlier this week.
WHO defines a public health emergency of international concern as “an extraordinary event” that constitutes a “public health risk to other States through the international spread of disease” and “to potentially require a coordinated international response.” Previous emergencies have included Ebola, Zika and H1N1.
Here are the countries with reported cases so far
The World Health Organization declared the novel coronavirus outbreak a public health emergency of international concern, after an emergency committee reconvened Thursday in Geneva.
Here is the current tally of cases -- and deaths -- reported from around the world.