With coronavirus infections continuing to surge in California ahead of Thanksgiving, public health officials urged those who travel during the holiday to quarantine for 14 days and said more drastic restrictions could be necessary if case rates continue to rise.

The urgent warnings come after economic reopenings were rolled back in some parts of the state and it became clear that hard-hit places such as Los Angeles County would not see their restrictions eased for the foreseeable future amid the widespread COVID-19 pandemic.

After declining earlier in the fall, California’s weekly cases have doubled in the past month. The Golden State is now averaging about 6,300 new cases a day over the past week, up from about 3,200 a month ago, according to a Times analysis. COVID-19 hospitalizations have risen 50% in the last month, and the coronavirus positive test rate has climbed by nearly 70%, with 4.4% of test results coming back positive over the past week, up from 2.6% a month ago.

The state as a whole hit 1 million confirmed cases Thursday, another grim milestone in a year full of them. In a sign of the worsening conditions, the drive-through testing site at Dodger Stadium has been flooded with people in recent days.

If the surge continues in L.A. County, “additional actions” could become necessary to bring the rate of transmission back under control, Public Health Director Barbara Ferrer said Thursday.

Though she didn’t elaborate on what potential new measures could be implemented, Ferrer emphasized that L.A. County remains on a knife’s edge and that everyone needs to do their part to keep conditions from worsening.

“We all need to act now,” she said during a media briefing. “The actions we take today, tomorrow and next week have tremendous impact on the health and well-being of many, many people across the county. If, collectively, we fail to stop the acceleration of new cases, we will have no choice but to look at additional actions.”

There has been debate about whether California might need to impose further restrictions if COVID-19 continues to spread. That would be bad news for retailers, who have been battered by the shutdowns and were hoping to finally see some relief during the typically busy holiday season.

Dr. John Swartzberg, an infectious-disease expert at UC Berkeley, said earlier this week that he believes the novel coronavirus is likely to swamp California in December and parts of the state economy will have to be shut down.

“Within a month after Thanksgiving, the number of cases is going to be up significantly,” Swartzberg said. “California is going to be very worried, and we will start to see things close down.”

L.A. County is recommending that residents don’t travel out of state for the holiday and that if they do, they quarantine for 14 days upon their return.

“If you are going to travel — which we are recommending you not do, we are actually recommending this Thanksgiving be a stay-at-home Thanksgiving — but if you are going to travel, we do ask when you come back that you quarantine for 14 days,” Ferrer said. “And the tighter you can restrict your activities over those 14 days, the better off we all are.”

Though the idea of not seeing family and friends after such a difficult year may strike some as untenable or unreasonable, health officials have repeatedly warned that gathering with those outside one’s immediate household heightens the risk of transmitting the disease.

Ferrer acknowledged it was a sacrifice, saying she won’t get to see her grandchildren for the holiday because they live in another state.

“Like all of you, I wish things were really different. But they’re not,” she said. “And my feeling is I don’t want to be one of the people that’s contributing to not only increasing cases that restrict our ability to continue with our recovery journey, but increasing cases that could result in other people getting sick and even dying.”

California has generally banned large gatherings and says smaller ones of no more than three households may be held outdoors with limitations, including time limits and requirements that attendees physically distance and wear face coverings.

L.A. County, like California as a whole, is seeing a renewed surge in coronavirus infections that shows no signs of dissipating. As of Nov. 3, the average number of daily cases in the county was 1,464 — up from 988 a month prior, Ferrer said.

Recent counts have been even higher. On Thursday, Ferrer reported 2,533 new cases.

The county is also starting to see hospitalizations climb. On Thursday, there were 953 COVID-19 patients in hospitals countywide — up from 777 on Nov. 2, Ferrer said.

Given that it usually takes a few weeks for a crush of cases to result in a corresponding increase in hospitalizations and deaths, Ferrer said that “we most likely haven’t yet seen the full consequence of the surge in cases we recently experienced.”

“While we’ve made impressive strides in caring for people who are ill with the virus, this much of an increase in cases may very well result in tremendous suffering and tragic deaths down the road,” she said.

So far, the county has not seen an uptick in deaths corresponding to the surge. In fact, as of Nov. 2, the average number of deaths per day in the county was 10, which “is the lowest number that we have seen since the very early days of the pandemic,” Ferrer said.

Still, she emphasized, “It’s going to take all of us to avoid increased heartbreak.”

Times staff writers Rong-Gong Lin II and Maura Dolan in San Francisco contributed to this report.