I agree with you. Viruses are not contagious pathogens, but I believe they can have an effect when injected. I do believe they are detox programs for the cells.
What would be the effect of injecting viruses, maybe even from other species? If an immune response was elicited would the immune response be desirable? Is it a good idea to get an immune reaction to a detox program? Would that hobble the immune system so another pathogen, say an intracellular parasite, could get a foothold?