From the Washington Post:
New recommendations from federal health officials this week on when vaccinated Americans should don face masks came with a startling bolt of news: People who have had their shots and become infected with the delta variant of the coronavirus can harbor large amounts of virus just like unvaccinated people. That means they could become spreaders of the disease and should return to wearing masks indoors in certain situations, including when vulnerable people are present.
But the Centers for Disease Control and Prevention did not publish the new research. In the text of the updated masking guidance, the agency merely cited “CDC COVID-19 Response Team, unpublished data, 2021.” Some outside scientists have their own message: Show us the data. “They’re making a claim that people with delta who are vaccinated and unvaccinated have similar levels of viral load, but nobody knows what that means,” said Gregg Gonsalves, an associate professor at the Yale School of Public Health. “It’s meaningless unless we see the data.”