Transcript for Americans urged to reconsider travel to China amid coronavirus outbreak
As of today the CDC has reported five cases of the novel corona virus infection here in the United States. China has now reported more than 4500. Cases. Americans should know that this is a potentially very serious public health threat. But at this point Americans should not worry for there own safety. This is a very fast moving constantly changing situation. Doctor Redfield and doctor doubt she will walk through some more details of the current situation and response. Part of the risk we face right now is that we don't yet know everything we need to know about this virus. But oh what emphasize that does not prevent us from preparing and responding. We have the experience of responding to two earlier corona viruses that emerged to cause serious illness in people saw ours embers. And we have experience responding to bird flu outbreaks in Asia. One challenge is that with an emerging virus like this. Our current assessments are based on and on certain denominator. Our denominator. Is the 4500 plus cases that have been identified in China. As well as more than sixty cases in other countries. But these early cases are naturally the most severe cases because patients presented themselves to health care providers. How does that skew our understanding. Of the virus. First. We're still determining the real speed of spread of this disease which is represented by a number known as. Which is the average number of additional people infected by a given person with the disease. One paper found are not estimates for this virus ranging from one point five. To 3.5. As compared with say a number of twelve. To eighteen for measles. Were also still learning about the severity. Of the virus. Currently China is reporting more than 100 doubts from the more than 4500. Cases. That is a high rate. But again the cases that have been identified skew to the severe including patients who were older or have other illnesses. The mortality rate may drop over time as we identify. A broader set of cases. We're also working to understand the incubation period. This number varies for corona viruses with extremes being anywhere from two. To fourteen days. That number could be higher or lower for this virus. Finally we're working to determine whether there is asymptomatic. Transmission. Normally with the corona virus we see more viral shedding and more transmission when a person is more symptomatic. China has reported there may be evidence is asymptomatic transmission. All of these questions must and will be answered in order provided proper risk assessment. But they are not stopping us from focusing on applying tried and true public health methods in the mean time. The playbook for responding to an infectious disease outbreak is relatively simple at ball tight here. You identify cases isolate people diagnosed them and treat them the new track down all the contacts of the infected person. And you do the same with those people and the same with contacts of contacts if necessary. That approach is now public health departments and health care providers working with the CDC are handling the case here in the United States. And I am very grateful the hard work that they are all doing together. This kind of work coupled with studies and analysis is also how we answer the questions I described earlier. On January the sixth we offered to send a CDC team to China that could assist with these public health efforts. I reiterated that offer when I spoke to China's minister of health on Monday. And it was reiterated again via the world health organization's leadership today in Beijing. We are urging China. More cooperation and transparency are the most important steps you can take toward a more effective response. Beyond that all options for dealing with infectious disease spread have to be on the table including travel restrictions. But diseases are not terribly good respecting borders. So would have to assess carefully whether the evidence recommends any steps the on the thoroughly tested happens I just described. Health care provider should be on the look out for patients with travel history to China especially Hubei Province. N for relevant symptoms. Late on Monday the CDC in the State Department issued a level three travel advisory for all of China. This higher level of alert means that Americans should reconsider or postpone travel to any part of China. The State Department has also maintained what they call it level four warning for who bait meaning Americans should not trouble there. In closing. I'll remind the American people want more time. We are working hard to keep you safe. We are constantly preparing for the possibility that the situation could worsen. And your health and safety has been and will be our top priority.
This transcript has been automatically generated and may not be 100% accurate.