It's difficult to gauge, since few economic studies have concerned themselves with it.

But I've found one mentioning that a disease like the 1957 Flu would reduce world GDP by 2%, and one like the Spanish Flu by 4.8%. The 2009 Flu cost 0.3%.

I think that makes around 2% a reasonable estimate. I'm suspecting most of the damage will come from the quarantines rather than work hours lost.

https://www.reuters.com/article/us-reutersmagazine-davos-flu-economy-idUSBRE90K0F820130121

I'm from Canada and have been in Spain for the past week. Things escalated exponentially from 1 week ago to today. Tourist sites closing, flights cancelled. It's pretty crazy

Crap. That's not good at all. :(

Edit: Forgot to mention that there are 2 confirmed cases of the coronavirus where I live right now.

If it is the case it would basically make the whole year pretty shitty. But if it comes back in the fall countries should be more prepared. 

Our local public schools in Ann Arbor Michigan have closed for the next three weeks and the university has switched to online courses for the rest of the semester. We've only had two cases in the state so I'm surprised the public schools acted so quickly, I was expecting them to wait it out another week.

Someday I'd be really interested to talk to an expert on this particular virus and find out what about it made everyone take action so drastically. This is a much more notable reaction than I think the world has ever had for a single disease. Perhaps that's just because we have so much more information than we've ever had before, travel is easier than ever, or is this specific virus so much worse than Ebola or previous SARS strains that it required this level of response even if all other things were equal.

https://www.google.com/amp/s/www.nytimes.com/interactive/2020/us/coronavirus-us-cases.amp.html

NYT has Michigan at 12 cases.

Oh? Last I heard it was 2, but I suppose that was two days ago. To be fair one of them is down the street at the hospital so I can understand the concern for local schools. 

Brazilian President Jair Bolsonaro reportedly tests positive for coronavirus after his press secretary Fabio Wajngarten tested positive for it. Bolsonaro, Wajngarten, and staffers were guests at Mar-a-Lago over the weekend. Wajngarten posed for a photo on Saturday with both the President and Vice President of the United States

Schools will be closing in Ontario for the next three weeks. Some Quebec schools are closed today to decide what they'll be doing for the next few weeks. My gym started doing some extra stuff like keeping doors open at all times so people don't have to touch them, not handing out the cards we usually need to get in crossfit classes, asking us to disinfect everything that we use (mats, slam balls, weights, etc...)

Yes, 2% of the world's GDP is already around $1.6 trillion I believe.

Of course, if you take into account stocks and bonds being wiped out, this number would be substantially larger.