The study behind new CDC’s mask guidance found vaccinated people can spread delta variant.

CDC Report: Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021 – Centers for Disease Control and Prevention

Commentaries:

The Study Behind CDC’s Mask Guidance Found Vaccinated People Can Spread Delta Variant – NPR

What Delta has changed in the Covid pandemic — and what it hasn’t – STAT

Commentary on Twitter (thread – click for more)

New @CDCMMWR on the Delta variant public gathering outbreak (incl "densely packed indoor events") in Barnstable Co involving 469 people, 74% among vaccinated, w/ similar viral load (Ct) as non-vaccinated. https://t.co/67sPljvaSQ pic.twitter.com/JNpfGD9qkB

— Eric Topol (@EricTopol) July 30, 2021