The CDC is always in a tough spot when facing a new infection. Reactions to such an event are one of those damned if you do, damned if you don't moments. Ultimately, an emerging infection can go pandemic very quickly, or peter out and disappear from the radar. In the early stages, there is no way to know what path it will take. Therefore, if you sound the alarm and it disappears, people question why there was concern and may be less likely to take precautions during the next outbreak. A fairly good example of this is the H1N1 swine inluenza outbreak from 2009. While it was certainly worse than a normal flu season, it was hardly catastrophic. Obviously, when they miss a big disease, everyone asks why they didn't do their job.
While this novel coronavirus is certainly concerning, it does have some traits that seem to be of less concern. First, contrary to the recent media panic, this disease has been popping up in the middle east for a couple years now. While the incidence of cases seems to have increased, we have not see wide outbreaks. Secondly, it does not appear to transmit well between humans. Those affected almost always have close exposure to a reservoir source (camels) or are healthcare workers in direct contact with the infected. These two taken together suggest that this virus may not be capable of sustained human to human transmission. After all, humans are an accidental host. This thing is used to growing in camels. However, close observation is warranted. This disease may be a single mutation away from better transmissibility. Even more concerning is the chance of what is known as a recombination event. Because the genome of coronaviruses is segmented, there is the potential for what is known as recombination events. This occurs when a cell is simultaneously infected by two distinct strains of a virus. You can theoretically obtain "daughter" viruses that carry the pathogenicity of MERS-CoV with the infectivity of a more common human coronavirus.
Yeah, I read it's not easily spread human-human. From what I've read the only way for it to spread is through close contact with someone or something infected.
