On 2020-07-08 a superspreading event most likely occurred in California. 5 days later (2020-07-13) it started to super-spread through the community. A total of 64 copies of this genome (that represents the core of the outbreak), were reported in Gisaid, a proxy for primary transmissions, along with 19 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 2020-07-18, 10 days after it started, with 2777 sequences found in total.
The last sequence of the superspreading event was collected on 2020-10-26.