Just a few months ago, this virus didn't exist in humans. By Monday morning, it has killed more than 3,800 people and infected more than 108,000 others worldwide.
Every day, CNN readers ask sharp questions about the mysterious novel coronavirus. And each weekday, we'll select some of the top questions and get you the answers.
Here are some of the questions submitted over the weekend:
Q. Why waste a test kit on a person without symptoms?
Some people with coronavirus have mild or no symptoms. And in some cases, symptoms don't appear until up to 14 days after infection.
During that incubation period, it's possible to get coronavirus from someone with no symptoms. It's also possible you may have coronavirus without feeling sick and are accidentally infecting others.
So anyone who has had close contact with someone known to have coronavirus should ask a health care provider about getting tested, the US Centers for Disease Control and Prevention said.
Anyone who recently traveled to a part of the world where coronavirus is widespread should do the same.
Q. How can someone pass along coronavirus when asymptomatic? If not sneezing or coughing, how can they infect others?
It's easy for asymptomatic people with coronavirus to spread the illness, said Dr. Anne Rimoin, an epidemiology professor at UCLA's School of Public Health.
"Certainly, when you speak, sometimes you'll spit a little bit," Rimoin said. "You'll rub your nose. You'll touch your mouth. You'll rub your eyes. And then you'll touch other surfaces, and then you will be spreading virus if you are infected and shedding asymptomatically."
Doctors stress that the best way to prevent getting coronavirus is not by wearing face masks, since they often cause more harm than good.
Q. Can coronavirus go through skin and into the body?
"It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads," the CDC says.
More often than not, people get coronavirus through respiratory droplets produced when an infected person coughs or sneezes.
"These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs," the CDC says.
The World Health Organization recommends staying at least 3 feet (1 meter) away from anyone who may be infected.
Q. If a coronavirus patient does progress to pneumonia, what antibiotics if any have proven to be effective?
No antibiotics are effective against coronavirus because the disease is a viral infection, not a bacterial infection.
"However, if you are hospitalized for the [coronavirus], you may receive antibiotics because bacterial co-infection is possible," the World Health Organization says.
For now, coronavirus patients get "supportive" treatment, "which means giving fluids, medicine to reduce fever, and, in severe cases, supplemental oxygen," the Harvard Medical School says.
Scientists are working on developing a vaccine. But it will take months before clinical trials start, and more than a year before a vaccine could become available.
Q. If infected with coronavirus, can you survive it and recover?
Absolutely. The vast majority of people with coronavirus survive.
Last week, the director of the National Institute of Allergy and Infectious Diseases estimated the death rate is "about 2%."
But the true death rate might be much lower, since some coronavirus survivors might not have been tested and might not have had their cases reported.
Q. After recovering from coronavirus, does the recovered patient have immunity to the virus?
It's too early to know for sure. But other coronaviruses, like ones that cause the common cold, might give us clues.
With "common cold coronaviruses, you don't actually have immunity that lasts for very long, and so we don't know the answer with this specific coronavirus," said Dr. Celine Gounder, a professor of medicine and infectious diseases at the New York University School of Medicine.
"If you recover, are you immune? And if you are immune, how long does that last? And that's actually going to be one of the challenges with designing a vaccine is how do you actually cause the immunity to last long enough to protect you."
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