Study in England showed one dose of COVID-19 vaccine can cut household transmission by up to half – This protection is on top of the reduced risk of a vaccinated person developing symptomatic infection, which is around 60 to 65% after the first dose

News release: One dose of COVID-19 vaccine can cut household transmission by up to half – Public Health England

Original study (preprint): Impact of vaccination on household transmission of SARS-COV-2 in England – Public Health England

Commentaries: Covid-19: One dose of vaccine cuts risk of passing on infection by as much as 50%, research shows – The BMJ AND Covid: One dose of vaccine halves transmission – study – BBC