On 2020-06-20 a superspreading event most likely occurred in Japan. 34 days later (2020-07-24) it started to super-spread through the community. A total of 83 copies of this genome (that represents the core of the outbreak), were reported in Gisaid, a proxy for primary transmissions, along with 591 genomes that are one-step mutation with respect to the core genome (a proxy for secondary transmissions). The signature for the likely superspreading event ends at about 2020-08-04, 45 days after it started, with 6339 sequences found in total.
The last sequence of the superspreading event was collected on 2020-08-30.