Good question. The whole "create a disease to sell the cure/vaccine" has been a stable on fiction and conspiracy theories but I don't think it is explicitly illegal, mostly because no one thought someone would actually stoop so low in real life.
You can probably find laws about undue viral research, as with Gain of Function and such, and attempts to establish a monopoly or cartel from the big pharma controlling the patent, but directly there is no one law explicitly declaring this illegal. You can bet you ass the billion dollar law firms will make it slide.
Maybe you could fit it in insider trading? It technically is, when you break down. You manipulated the market taking advantage of knowledge obtained in a illegal manner. I don't know I am no lawyer.