Los Angeles County Department of Public Health this week asked residents to wear face masks indoors, even if they are vaccinated, due to a rise in coronavirus cases.

The state of play: County health officials said the Delta variant, first detected in India, is rapidly spreading across the county's unvaccinated population. Cases in the county have doubled and hospitalizations are up by 30%, the Los Angeles Times notes.

• For Black residents, hospitalizations rose by 11% between May and June.
• About 51% of county residents are fully vaccinated.

What they're saying: "We have enough risk and enough unvaccinated people for Delta to pose a threat to our recovery. And masking up now could help prevent a resurgence in transmission," said L.A. County Public Health Director Barbara Ferrer, per the Times.

• "This is a precautionary recommendation, given that we don’t have all the information we wish we had."
• Ferrer pointed out that while vaccines are highly effective, there is "increasing evidence that a very small number of fully vaccinated individuals can become infected with the Delta variant and may be able to infect others."

The big picture: The rise in cases comes as more people question whether the vaccines can protect against variants. The CDC has doubled down on its own guidelines, saying that vaccinated individuals can unmask.

• "Vaccinated Americans have been deemed safe from variants so far including the Delta variant," Axios' Marisa Fernandez writes.

Go deeper: Delta variant threatens masking guidance