From the BBC website:
Public Health Scotland and the University of Glasgow monitored 300,000 NHS workers between 8 December - the first day of vaccination in Scotland - and 3 March.
The researchers looked at the records of people who lived with vaccinated and unvaccinated healthcare workers, finding the workers who had had one dose were at least 30% less likely to have passed the virus on.
Given that people living with healthcare workers could also catch the virus from other sources, researchers say the 30% figure is a low estimate.
Those who had had both doses of vaccine were found to have been at least 54% less likely to have transmitted the virus.