The Omicron surge has hit California, with new coronavirus cases climbing rapidly and public health officials in some parts of the state warning that hospitals could be hit hard by a surge in patients in the coming weeks.

Data show new coronavirus cases in the state jumping in recent days, with Los Angeles County health officials expecting the Omicron variant to overtake the Delta strain within two weeks. But officials stressed that vaccinations, and especially booster shots, will give Californians who receive them strong protection against serious illness, which could make the coming surge less deadly than last year’s devastating winter.

“It’s not a time to panic, but a time to be vigilant,” said San Francisco Health Director Dr. Grant Colfax.

Whether hospitalizations will surpass last year’s numbers depends on several factors: how severe Omicron ends up being and whether residents comply with mask mandates, avoid crowded risky indoor public settings and get vaccinated or boosted.