The Spiez Laboratory (Switzerland) released a promising study:

"In vitro virucidal activity of Echinaforce®, an Echinacea purpurea preparation, against coronaviruses, including common cold coronavirus 229E and SARS-CoV-2"

https://virologyj.biomedcentral.com/articles/10.1186/s12985-020-01401-2

More Info about the Spiez Laboratory:

https://www.labor-spiez.ch/en/lab/