Coronaviruses can be spread via coughing, sneezing or touching someone who is infected. They are a large family of viruses with many types that can cause infections ranging from the common cold to SARS, or severe acute respiratory syndrome.
So far, two cases have been reported in Thailand and one in Japan. The United States has implemented additional checks for passengers arriving from Wuhan at airports in New York, San Francisco and Los Angeles.
Chinese authorities have suggested that no human-to-human transmission has been confirmed. However, the Wuhan Municipal Health Commission admitted that it "cannot be excluded."