Parthenium integrifolium has ZERO effect on respiratory viruses and contains none of the medicinal components that do.
The URL that you posted has the chemical analysis. ZERO Quercetins, ZERO quinolines.
Instead, start by taking higher doses of Vitamin C. Timed release is good if you can't keep to a shchedule of several times per day..
Take Zinc. Get multiple chemical forms, and take one of each. Your body will absorb some of the Z. citrate, some of the Z. picolinate, some of the Z acetate, some of the Z sulfate. It may take some hunting to find different brands with different ingredients.
Then, get some Quercetin. Or find a source of Artemisia annua, a chinese herb. Do not use the European Absinth because it has completely different chemical components.
Or look for Persicaria hydropiper which actually grows wild as a weed in drainage ditches in the USA. It is called Waterpepper. It's related to the knotweed family. Aside from the wet habitat, this swelling where the leaves come from the stem is the main identifying feature.
You could also try a common weed called Yarrow (Achillea millefolium) which is also described in the medical literature.
Use Pubmed to learn which things work and which do not.
https://pubmed.ncbi.nlm.nih.gov/