Why is California still requiring masks at school? Here’s what experts say By Kellie Hwang California’s new COVID-19 health rules for K-12 schools differ from CDC guidance in one key way: The state will require masks indoors for all students and adults who are sharing spaces with students, whereas the CDC recommends mask-wearing only for students and staff who are not yet vaccinated. The state’s public health department said its approach takes into account “current unknowns” associated with the emergence of the highly contagious delta variant, as well as the difficulties of tracking vaccination status. Hours after the state unveiled the guidelines, officials indicated in a tweet that they would “clarify” the rules and take into account “local schools’ experience in keeping students and educators safe.”