LOS ANGELES (BLOOMBERG) - For weeks, Los Angeles officials have warned residents of a surge in Covid-19 cases tied to the holidays. To make the point, they shut all dining at restaurants and even suggested people wear masks in their own homes when family visits.
"Assume everyone you would see is infectious," Mayor Eric Garcetti said three days before Thanksgiving at the end of November.
Since then, the nation's second-largest city and its suburbs have become America's worst-hit metro area. San Bernardino, Riverside and Los Angeles now rank one, two and three, respectively, among big US counties with the highest rates of virus cases per capita in the past week.
New cases, deaths and hospitalisations all hit records in Los Angeles this week, including 5,424 reported in hospitals on Saturday (Dec 19).
Many factors help explain why, but it may come down to one key difference between now and previous Covid-19 surges.
As Dr Rita Burke, an assistant professor of preventive clinical medicine at the University of Southern California's Keck School of Medicine, put it: "In the spring, there was a lot of fear. People really stayed home."
Whatever the precise cause, the cost has become alarmingly clear. Hospitals in Southern California are converting space after the region's intensive-care units hit full capacity. They have moved in reserve ventilators and postponed elective surgeries after starting some days with no ICU beds at all.
"We are getting crushed," said Dr Brad Spellberg, chief medical officer at Los Angeles County-University of Southern California Medical Centre.
Los Angeles county public health director Barbara Ferrer choked up at a news conference earlier this month when she read the rising death tally. Last Thursday, Mayor Garcetti said his nine-year-old daughter tested positive.
The numbers are surging in a region and state that, with a few exceptions, treated the virus seriously from the start. Southern California had one of the first cases in the nation in January, and local officials put out mandatory stay-at-home orders in March.
Pockets of resistance emerged, including protests against the shutdowns in conservative Huntington Beach and citizens who marched in great, closely packed numbers during the social unrest of the past summer. But Southern Californians largely complied with health precautions.
Many businesses, including movie theatres, theme parks, stadiums and museums have not been open to the public for nine months. The number of people in Los Angeles county who have gotten sick is the highest in the country at more than 600,000, or one out of every 17 residents. The latest 100,000 cases were added in just eight days.
Los Angeles is one of the most densely populated urban areas in America. Even with fewer high-rises than New York or Chicago, many of its residents live in apartments or houses with parents and grandparents. Many are of modest means, performing jobs where they need to go in to work.
"They don't have an option to go someplace else," Mr Garcetti said. "They don't have their own bedroom. It's shared spaces, and the virus will spread."
Southern Californians successfully stemmed two earlier surges, said medical director Nancy Gin from Kaiser Permanente, a healthcare provider that treats some 4.4 million members in the region.
As summer wore on, more businesses and schools reopened.
Despite the warnings, hundreds of thousands of people travelled or gathered over the Thanksgiving holiday, contributing to the current spike. Many healthcare officials fear the coming holidays will worsen those numbers.
"All the gains we've made in treating patients in the ICU, which have been reflected in decreasing mortality rates, we're going to lose," said Dr John Swartzberg, clinical professor emeritus at the University of California, Berkeley's School of Public Health. "And that's heartbreaking."
Even though mask wearing is commonplace from the region's shopping boulevards to its hiking trails, many residents still let their guard down. Traffic on the city's streets and freeways has picked up.
Mobile device location data analysed by Orbital Insight show that traffic on California roads dropped slightly in the days after many of the lockdowns began early this month. But the effect has been slight, with movement on any given day hovering around 80 per cent of its pre-pandemic norm.
In the past month, local officials have prosecuted participants of mass gatherings in downtown Los Angeles and in the far north suburb of Palmdale, where 158 people were arrested at a house party on Dec 5.
In New York, the state got hit so hard early in the pandemic that many residents have first-hand experience with the illness, said Dr Robert Kim-Farley a professor-in-residence of public health at the University of California, Los Angeles.
In California, pandemic fatigue has set in amid "some sort of mandatory orders for so long", he said. "We need to fight this viral wildfire with all the means in our possession."
San Bernardino county, a region of more than two million people just east of Los Angeles, has seen patients getting younger, with 18- to 29-year-olds accounting for a big leap in cases, according to Dr Corwin Porter, the county's director of public health.
Part of the problem is that Covid-19 can be transmitted by people without symptoms. "We have a lot of folks who don't even know they're carrying it," he said.
Spread between families and friends accounts for the majority of the cases, which have been tied to everything from Thanksgiving dinners to funerals. "We have weddings that have showed up as indicators," he said.
Contact tracing is a challenge: Only about 60 per cent of those who test positive even return phone calls from local health departments.
Sick people often say they have only been to grocery stores, even though it is unlikely they actually got it there, said Mr Jose Arballo, a spokesman for the department of public health in Riverside county, where 2.5 million people live south-east of Los Angeles. "They never say they're doing things they shouldn't be doing," he said.
Public outcry over closures of playgrounds, one of the few areas children can get exercise, prompted the state and county of Los Angeles to backtrack from restrictions this month.
The state's restaurant association also won a suit to block restrictions on closures of outdoor dining in Los Angeles, though the state order to do so remains in effect. County officials, meanwhile, are challenging the city of Manhattan Beach's efforts to declare outdoor seating areas near restaurants as public parks so they can remain open.
"Policymakers must resist the temptation to make matters worse with unnecessary restrictions on safe business activity," Mr Jordan Bruneau, the communications director for the non-profit California Policy Centre, wrote in a release last Friday. "There doesn't seem to be a clear correlation between economic shutdowns and contagion."
Even some healthcare experts say the latest lockdowns do not seem to be reining in the outbreak, at least not yet. France's lockdown orders took about two weeks to show an effect, according to Dr George Rutherford, the head of infectious disease and global epidemiology at the University of California San Francisco.
"Two weeks for us would be this coming Monday, and I don't see any evidence for it yet," he said. "We need to start seeing serious drop offs, by the thousands or tens of thousands, before I'd be able to say, 'Yes, this worked'."
Dr Rutherford said more restrictive measures may be needed to stop the surge.
Mayor Garcetti urged residents to stay the course and limit interactions with people outside their homes.
"It doesn't mean that the things we've done have failed," he said of the rising cases numbers. "We'll never be able to quantify how many lives we are saving by having done those things."