CDC: The New Chinese Virus (2019-nCoV) is Four to Six Times Less Contagious than Measles, the Incubation is 1 to 14 DaysJanuary 28, 2020
The U.S. Centers for Disease Control has two conclusions about 2019-nCoV, the new Chinese virus that began in Wuhan circa Dec. 10th, 2019.
First, it is four to six times less contagious than measles, which is the most contagious virus in circulation.
Second, they have seen no evidence of asymptomatic patients spreading the virus (as has been earlier reported by some media). Asymptomatic means you are infected but show or have no symptoms. Patients infected with 2019-nCoV and do not have symptoms — are not, repeat not, spreading the virus.
To repeat for emphasis: only those with symptoms are infectious.
Or, as CNBC put it “CDC hasn’t seen any evidence that shows it’s contagious before symptoms appear.”
This is great news, obviously.
The other key conclusion by the U.S. CDC is the incubation period is between one and fourteen days. This range will likely shrink as more data becomes available.
Finally, the R naught score (the math used to determine how contagious a virus is) for 2019-nCoV is between 1.5 and 3.0, meaning it is not a highly contagious virus. Pretty run of the mill, especially at the lower end of the range. The seasonal flu has an R score of 1.3, while the score for measles, for example, is 12 to 18. My guess is that as more information about the 2019-nCoV virus becomes available, its R score will decline, likely settling near the R score of seasonal flu.