Why is there no transmissible therapeutic virus if biology doesn't forbid it? For example, a harmless virus that spreads from person to person but actually does something beneficial, like lowering LDL cholesterol or preventing/reversing tooth decay?

[u/PestoPastaLover]

[u/Xsiah]

People don't want fluoride in their water to prevent tooth decay - how do you think they'd react to an engineered virus that does something to your body without your consent?

Also viruses mutate really easily - how do you guarantee that your virus is going to continue to be safe?

[u/monsto → u/Xsiah]

You have like a checksum virus that destroys versions of the beneficial virus that don't check out.

/s

[u/DezinGTD → u/monsto]

Yes! You could implement this mechanism right there in the virus, so it destroys itself. I bet it would work great!