Even before the new CDC guidance, it was not difficult to predict the state would ultimately land on a recommendation, as opposed to a mandate. Currently, mandates are only in effect in two counties — Los Angeles and Yolo — while several others, including every Bay Area county except Solano, are recommending masks. 

What remains to be seen is if counties will convert mask recommendations into mandates following the updated CDC and state guidance.

The CDC said the change in guidance is based on new evidence showing that while fully vaccinated individuals are protected against severe disease from the delta variant, they can transmit it to unvaccinated individuals more easily than other strains of the virus.

CDC Director Dr. Rochelle Walensky said that when earlier strains of the virus were dominant, infected vaccinated people were found to have low levels of virus in their nose and throats and were deemed unlikely to spread the virus. That has changed with the delta variant, where Walensky said the level of virus in infected vaccinated people is “indistinguishable” from the level of virus in infected unvaccinated people.

The Associated Press contributed to this report.