C3G has similar activities . It's high in elderberry juice as reported in this thread.
(https://bioenergetic.forum/topic/847/cyanidin-3-o-glucoside-c3g-the-next-polyphenolic-star?_=1724528336146)

And elderberry juice is traditionally given when you have the flue in Germany.

There's also some study showing anti-viral effects specifically in Covid.

https://pubmed.ncbi.nlm.nih.gov/35807916/

https://pubmed.ncbi.nlm.nih.gov/35431537/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856223/