Governor Newsom and state public health officials continue to warn about a winter surge of COVID cases in California, even though 90% of Californians have received at least one dose of the vaccine and more than 60% are fully vaccinated. 

In recent weeks California's case rate per 100,000 people has spiked and the state has moved back into the red zone on the CDC map, despite mask and vaccine mandates. 

Why is this happening, and could we be looking at a surge as bad as previous ones? 

To discuss, KCBS Radio political reporter Doug Sovern spoke with Dr. Bob Wachter, Professor and Chair of the Department of Medicine at UCSF.