The delta variant of the coronavirus roared into California midsummer, striking hard even in places where many people were vaccinated. Cases spiked. Hospitals again began to swell with patients. The daily death toll climbed into the triple digits for the first time in months.
But after a season in which the highly transmissible variant wreaked havoc on the nation, California is reporting sustained progress against delta.
Earlier this week, California dropped from "high" to "substantial" virus spread, according to the Centers for Disease Control and Prevention. It later bounced back up, but total new cases per 100,000 residents are still lower than any other state. The change in CDC designation - a barometer of how well states are doing in combating the virus - was celebrated by public health officials, who suggested it was a signal that California could be close to a turning point.
An aggressive push for vaccines, coupled with masks mandates at the local level and a public largely willing to go along with them, appear to have helped flatten the state's curve, experts said.
"California, as compared to many other states in the nation, took rapid steps to recognize the extent of the problem and to apply more covid control measures," said Robert Kim-Farley, a infectious-disease expert at UCLA Fielding School of Public Health. "I think if California had not taken these steps to curb transmission, we could have ended up with much higher levels."
The fight against delta is far from over in the Golden State, which still faces a host of challenges in containing cases. Though infections have dropped in California's population hubs in recent weeks, they remain high in parts of the Central Valley and rural north. An influx of patients has overwhelmed some intensive care units in those regions.
Compounding the problem, California hospitals are facing staffing shortages. Medical workers have struggled with burnout, and surges in other states have created intense competition for nurses, said Bryan Bucklew, president and chief executive of Hospital Council of Northern & Central California, a nonprofit trade association.
"The numbers may be flattening, but the impact to the health-care system is extremely challenging," he said. "We have a good handle on how to treat covid, with monoclonal antibodies, vaccines. We just have a lot less staff. It's more of a workforce issue for us than a covid issue."
Statewide, infections are still far higher than they were early in the summer, averaging about 9,300 new cases per day now compared to 758 on July 1, according to tracking by The Washington Post.
But they're down from a summer peak of about 14,400 per day on average, the data shows. Hospitalizations have fallen statewide by about 10% over the past week. Positivity rates have also dropped recently, at a time when the state is administering more tests than at almost any point in the pandemic - another indicator that the spread is slowing.
Experts credit the state's embrace of public health measures.
More than 57% of the California's population is fully vaccinated, higher than the national average. Big cities such as Los Angeles and San Francisco have moved to require vaccines for activities like dining in restaurants and working out in gyms. Gov. Gavin Newsom, D, ordered the shots for state employees and workers in high-risk settings, and rolled out incentives that included the country's biggest vaccine lottery. And as delta spread, many of the state's most populous counties brought back requirements for wearing face coverings indoors.
"They remain an overall high vaccination state and have allowed for more local autonomy over non-pharmaceutical interventions, including excellent testing levels," said Howard Forman, head of the health-care management program at Yale School of Public Health. "It's never just one thing. But I think they have truly managed this better than most states."
"There will likely be more outbreaks in areas of California that have lower immunity (acquired through infection OR vaccination)," Forman added in an email. "But the population centers seem to have high levels of immunity."
Florida and Texas - populous states where vaccine and masking uptake is not as widespread - have battled more severe surges than California as delta has taken hold.
At its worst point over the summer, cases per 100,000 people in California rose to about 35 per day on average, according to The Post's analysis of state data. In Florida, where the governor has sought to ban public health mandates, per capita cases topped 100 during the peak of infections, and in Texas they've hovered around 60 for weeks, the data shows.
As of Thursday, California had 24 cases per 100,000 residents, less than half as many as Florida, with 55 per capita, and Texas with 59, according The Post's data.
John Swartzberg, an infectious-disease expert at the University of California at Berkeley, said California has benefited from a population that's generally receptive to public health directives. He said the attitude was rooted in the public health response to the AIDS crisis in the early 1980s.
"That established a culture primarily in the Bay Area, but it spread to Southern California, too," he said.
The recall election that Newsom survived Tuesday gauged Californians' views on their state's approach to the pandemic. The governor's Republican rivals criticized his aggressive lockdown orders, which effectively brought the state economy to a halt last year. He prevailed in a landslide. Exit polls showed a plurality of voters said the pandemic was their top issue in deciding their vote.
"In one sense, the recent recall election was a bit of a referendum on doing more rather than doing less for covid," said Kim-Farley, of UCLA. "That's indicative of the general California citizens' attitude towards wanting to do their part in helping to control the pandemic."
Swartzberg said the state's early action in issuing restrictions set the stage for later efforts to contain the virus. In May, as cases were plummeting and the CDC was loosening its mask guidelines, California officials decided to wait a month before lifting the state's mask mandate. That, too, may have insulated the state against the explosion in delta cases, according to Swartzberg.
"California very wisely deferred that for a month," he said. While it didn't prevent the virus from resurging, he said, "I think that helped us going into the delta pandemic."
The delta has proved harder to snuff out than earlier, less-infectious versions of the virus. The new academic year, the coming holiday season and cold weather, all forcing more people indoors, could unleash yet another viral wave. Swartzberg warned that loosening public health measures too soon could reverse California's hard-fought gains.
"California has not been an exception to making this mistake," he said. "There's a pattern of surge, things get better, loosen up too soon. That stepwise fashion has been the pattern we've seen here and nationally."
"We need to learn from our past experience," he added. "I'm very concerned that we keep our foot on the brake for the rest of the fall and through January."