Before revision:  We further illustrate the central role of these two communities in the emergence of COVID-related communities. Second, we study the differences between these two communities. /r/ Coronavirus is recommended as the official community for COVID-19 on Reddit, while /r  /  China _flu adopts a loose moderation practice.
After revision:  We further illustrate the central role of these two communities from the beginning of COVID-19 to the end of September 2020. We show that new users of /r/ Coronavirus is recommended as the official community for COVID-19 on Reddit, while /r / China _flu adopts a loose moderation practice.