https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00648-4/fulltext

The Lancet on Interpretation

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.

Funding

National Institute for Health Research