Hard for it to spread faster than a respiratory bug unless it has some symptoms - coughs etc. The version of that idea that is feasible is intentional innoculations, which is basically a live attenuated vaccine.
The issue with COVID is that some people are hit hard and a lot of people develop hard to detect complications.
If you could modify the virus to avoid complications and avoid hitting some people very hard, you could have pretty effective way to innoculate population.
The thing you are after is a virus that has same basic spike protein for your immune system to recognize and only enough mechanism to multiply itself.
> The thing you are after is a virus that has same basic spike protein for your immune system to recognize and only enough mechanism to multiply itself.
The version of that that is feasible is a viral vector vaccine e.g., ChAdOx1.