China's health minister Ma Xiaowei Sunday said people can spread the coronavirus before they become symptomatic, according to an article on the CNN website.
It's much harder to contain a virus -- to track down a patient's contacts and quarantine them immediately -- if the patient was spreading the disease for days or weeks before they even realized they had it.
If the Chinese health minister is right, and there are some who doubt him according to the article,that means the five confirmed cases in the United States might have been infectious while traveling from Wuhan to Arizona, California, Illinois and Washington state, even if they had no symptoms at the time.
The CDC says there is no clear evidence that patients are infectious before symptom onset.
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