***
1. Find some vague criteria for what constitutes the symptoms that you want people to look for. Anything subjective that a lot of people can identify with is ideal. Let us take memory problems and/or confusion + a few common ones from the Covid list. Tiredness, aches and pains are common and subjective enough. (For covid19 the symptoms are: fever, dry cough, tiredness. Less common symptoms: aches and pains, sore throat, diarrhoea, loss of taste or smell, a rash, or discolouration of fingers or toes)
It would be a good idea to take something that is very common in old people so that we can use death from old age as proof of the lethality of the new virus.
***
2. Then we would need something biological to test. Any RNA sequence would do, as long as it is not present in the whole population. If it were, someone might claim herd immunity very quickly. Actually it could be an RNA sequence that does not really exist in humans but something that could exist as contamination in labs, e.g. in dust or water.
Comment: It's been pretty clear from the get-go that QAnon was a clever psyop, designed to divert the attention and energy of many sincere people from true problems. Forbes, along with the major social media platforms, is playing its part in lending it quasi-credibility with mainstream reporting.