Typical preparations, most especially those sold for vaping, turn out on examination to have ~2% of the amount of CBD advertised, where they have any. I.e., they have just enough that a crude test of presence shows something present.
That said, I buy from a premium dispensary and I have no idea what's vended in smoke shops.
I read one good-quality paper that reported an effect, and suggested plausible mechanisms. But the authors cautioned it needed more work before it could be recommended clinically. In particular, there was no hint it might prevent infection, or be useful to treat mild cases. The perhaps surprising bit was that THC interfered with the effect of the CBD.
The US NIH says that fluvoxamine is useful to treat serious cases. Any doctor can prescribe that.
CBD's effect on COVID-19 is to suppress the over-reaction of the immune system causing congestion and breathing problems. It does not interfere with the viral life cycle. So, it is useless to prevent COVID-19 infection.
In vitro analysis suggested that, in principle, ivermectin ought to help block COVID-19 virus in several ways. That generated interest to see if it would help.
The more reliable each study has been, the less effect it has shown. Something working great in test tubes (and even in mice) and failing when prescribed to actual people is totally unsurprising to anybody who works in medical research. Something promising that actually turns out to work clinically is always astonishing.
So, discounting promotion by people do lack long experience interpreting medical research results is not corrupt SUPPRESSION OF THE TRUTH. It is simple honest reporting, is doing you a favor, and you should welcome it.