Coronaviruses are named for the crown-like appearance of protein spikes on their surface.
This strain, COVID-19, is new. It’s believed to have started in Wuhan, China, a city with around 11 million people...
...at the Huanan Seafood Market that sold fish and meat, some of it from wildlife.
Some researchers think someone got sick after eating contaminated meat and infected others, creating a ripple effect around the world.
More than 100,000 people have been infected in over 60 countries.
Of those, the majority, over 53,000 people, have already recovered from the virus.
However, more than 3,000 have died worldwide; mortality rate estimates vary between 2% and 3.4%.
The highest mortality rate has been among people over 80 years of age.
Like the flu, those most at risk of complications are people over 60 years old and those with underlying health conditions.
However, there are some key differences between
COVID-19 and the flu.
Common symptoms, like fever and cough, are similar between the two.
But about 1 in 6 people becomes seriously ill and develops difficulty breathing, according to the World Health Organization.
Like the cold or flu, transmission is primarily thought to occur through droplets of mucus or saliva from infected people or close contact with them.
There have been reports of transmission from those who are infected and show no symptoms, but that's still being investigated.
Because it’s a new virus, people have not built up an immunity to it like with common flu strains.
There are vaccines for seasonal flu, but there is currently no vaccine for COVID-19.
Experts say the production of a vaccine is 12-18 months away, at the earliest.
The best defense against COVID-19, and viruses in general, is to wash hands regularly and thoroughly, and avoid prolonged contact with visibly ill people.
Face masks generally don't offer any protection, unless you're caring for someone with the virus.
However, if you're already sick, they can be effective in preventing the illness from spreading beyond yourself.
Working from home, calling in sick, and avoiding public places are also important steps you can take when infected to prevent spread.
The CDC recommends you call your doctor if you have flu-like symptoms and have had close contact with somebody with the virus, or traveled to/live in an area where with ongoing spread.