I haven't read the full paper, and it's pretty small data (maybe n=120 in total) but this would seem to suggest that there's about a 40% reduction in transmission associated with vaccination: https://www.thelancet.com/journals/laninf/article/PIIS1473-3...
I honestly don't understand how there wouldn't be protection from the vaccine. It's not a sterilising vaccine, but it does offer protection.
"SAR among household contacts exposed to fully vaccinated index cases was similar to household contacts exposed to unvaccinated index cases (25% [95% CI 15–35] for vaccinated vs 23% [15–31] for unvaccinated)."
In other words, once infected, there is no reduction. How effective are these boosters against Omikron infection, weeks and months down the line?
I honestly don't understand how there wouldn't be protection from the vaccine. It's not a sterilising vaccine, but it does offer protection.