Here is a pretty important preprint:

Infectious Viral Load

A group of researchers in Geneva performed the experiments that can actually tell us some facts about Delta and Omicron variants, and about the effect of vaccinations have on them. MSM and even public health agencies have been making a lot of claims, with zero or shoddy evidence.

Quote
In conclusion, this study provides strong evidence for higher infectiousness of the Delta VOC as well as a significantly lower infectiousness and a faster clearance of infectious virus in vaccinated individuals. In addition, we could show that Omicron has similar infectious viral loads than Delta VOC. Furthermore, we show a more detailed picture of viral load assessment in addition to overall virus isolation success, and that quantifying viral loads can give better insights into viral shedding kinetics in acute SARS-CoV-2 infection.

In short:
Delta was more infectious than previous variants of concern.
Vaccinated people can get infected but they shed very little infectious virus, for a shorter time.
PCR is not a reliable measure of infectious virus being shed. (my belief: "killed" virus fragments)
Not much difference between Delta and Omicron variants. (my belief: more people have immunity)
Five days post symptom onset is probably too short an isolation period. (my belief: eight days would be safer)

Educating anyone benefits everyone.