The article cites this U. of Oxford preprint: https://www.ox.ac.uk/news/2021-08-19-vaccines-still-effective-against-delta-variant-concern-says-oxford-led-study

The article cites this U. of Oxford preprint: https://www.ox.ac.uk/news/2021-08-19-vaccines-still-effective-against-delta-variant-concern-says-oxford-led-study-covid-0 https://www.ox.ac.uk/news/2021-08-19-vaccines-still-effectiv... It says: 'our data shows the potential for vaccinated individuals to still pass COVID-19 onto others, and the importance of testing and self-isolation to reduce transmission risk.'