Before revision:  A total of salient 11 topics are identified and then categorized into 10 themes, such as "  cases outside China (worldwide)," "COVID-19 outbreak in South Korea," "early signs of the outbreak in New York," "Diamond Princess cruise," "economic impact," "Preventive /Protective measures," "authorities," and "supply chain ". Results do not reveal treatment and /or symptoms related messages as a prevalent topic on Twitter.
After revision:  A total of salient 11 topics are identified and then categorized into ten themes, including " cases outside China (worldwide)," "COVID-19 outbreak in South Korea," "early signs of the outbreak in New York," "Diamond Princess cruise," "economic impact," "Preventive /Protective measures," "authorities," and "supply chain ". Results do not reveal treatment and /or symptoms related messages as a prevalent topic on Twitter.