Lancet study says vaccines do not reduce transmission. “Fully vaccinated individuals with breakthrough infections have peak viral load similar to unvaccinated cases & can efficiently transmit infection in household settings including to fully vaccinated” (www.thelancet.com)

Short excerpt

Vaccination reduces the risk of delta variant infection and accelerates viral clearance.
Nonetheless, fully vaccinated individuals with breakthrough infections have peak viral
load similar to unvaccinated cases and can efficiently transmit infection in household
settings, including to fully vaccinated contacts. Host–virus interactions early in
infection may shape the entire viral trajectory.