[Lewis Thomson (OP)]

Raymond has presented this idea about covid and would like some outside help finding answers.

"As I understand Omicron is very infectious and may be less "dangerous". Do we know what portion of the virus is "pathological"? If so, with genetic engineering, can scientist(s) develop a variant of COVID19 that is as infectious (or better still, more infectious) as Omicron but the "pathological" portions of the virus' genetic sequence engineered to be harmless?"

Discuss in the comments below...

[Origin]

We could try but I fear the 'law of unintended consequences' could bite us in the butt big time on that one.

[evan_au]

Do we know what portion of the virus is "pathological"?

There are many aspects that make a virus dangerous. For COVID:
1. the main cause of rapid death is damage to the alveoli of the lungs, severely reducing blood oxygenation. However, Omicron tends to infect the upper airways, which means that you breathe out more virus (more infectious), but do a lot less damage to the alveoli (less lethal).
2. the second cause of damage is that the virus can invade any cell expressing the ACE2 receptor; these infected cells are then attacked by the immune system. This includes the lining of blood vessels (causes clots throughout the body, affecting all organs) and astrocytes (nerve supporting cells; this causes loss of smell and brain damage).
3. Apparently, COVID can reactivate Epstein-Barr virus (which causes the brain fog of glandular fever; 95% of us have a latent infection) and exacerbate auto-antibodies (producing an auto-immune condition similar to lupus). These are some of the characteristics of Long COVID.

So Omicron seems to be less lethal on (1), seems to cause loss of smell in a smaller proportion of people, so maybe is better on (2); I have not seen a comparison of (3).
 
See "Multiple early factors anticipate post-acute COVID-19 sequelae":
https://www.cell.com/cell/fulltext/S0092-8674(22)00072-1

[Bored chemist]

Can we engineer our own less harmful variant of covid to build immunity?
Yes.
We call it a vaccine.

[wolfekeeper]

Traditionally to make a vaccine we would use evolution, we would pass it through another animal for a while, and overtime it would forget how to badly infect humans, but the mutated version would still be close enough that our bodies recognized it and built antibodies against it.

It works really well, and most childhood vaccinations were developed that way, but it's a bit slow, and knowing how long to pass it through other animals is an art, not entirely a science. Leave it too long and they'll be too different and the vaccination won't work, not long enough and it will still be too pathogenic.

[evan_au]

The other problem with attenuated live virus vaccines is that sometimes the virus "escapes" - this happened to the attenuated  polio vaccine.

Now, as well as trying to eliminate the "wild" polio virus, they also now have to try and eliminate the "escaped" virus.
See: https://en.wikipedia.org/wiki/Polio_vaccine#Vaccine-induced_polio