Figure 2.

Graph’s x-axis (dates from October 1, 2020, to October 1, 2021) is used as a timeline of key events and dynamic profile of imported virus strain B1.617.2 (delta) transmission during sporadic COVID-19 outbreaks in China. The delta COVID-19 variant was first detected in India in October 2020. The WHO declared the delta variant a “variant of concern” on May 10, 2021. On Mid-June 2021, the US Centers for Disease Control and Prevention upgraded its classification of delta from a “variant of interest” to a “variant of concern”.