You could actually read the study.
https://www.medrxiv.org/content/10.1...1.full.pdfOver 20% of positive, vaccinated individuals had low Ct-values (<20), a third of which were asymptomatic when tested. This highlights the need for additional studies of the immunological status of such vaccine escapes and how infectious they are. If such individuals carry high loads of active virus, asymptomatic vaccinated individuals may increasingly contribute to the ongoing pandemic as the proportion of vaccinated individuals grows.