It has been one of the most glaring unanswered questions of the coronavirus crisis: How much has the virus spread? A new study in Los Angeles County might help provide some answers.
Starting Friday, county health officials will begin testing the blood of 1,000 randomly selected residents, including those with no symptoms, to see if they have or had COVID-19. Using emerging technology that tests for antibodies to a virus, the study has the potential to shed light on the true mortality rate of the coronavirus, the efficacy of social distancing efforts and when this unprecedented clampdown on daily life could end.
Health officials and researchers say the results of this effort, known as serological testing, could paint the most complete picture yet of the sweep of the pandemic in the nation’s most populous county.
“Is it 1% of our population? Is it 10% of our population? That’s the difference between 80,000 adults and 800,000 adults. We have no idea,†said Dr. Paul Simon, chief science officer of the Los Angeles County Department of Public Health.
With the study’s launch, the county joins the growing ranks of governments and researchers that are turning to antibody tests as a new frontier in the campaign against COVID-19.
Antibody testing has already begun in Santa Clara County, with researchers drawing more than 3,000 people’s blood over two days last week at three drive-up testing sites. The Centers for Disease Control and Prevention began last week testing the blood of people living in coronavirus hot spots. And Thursday, German health officials announced plans to run Europe’s first large-scale antibody testing program.
So far most testing has been done with nasal swabs, meant to detect the presence of the virus. But the pool of those tested has skewed toward the very ill, as health officials have put the highest-risk patients at the front of the line.
With the new blood tests, scientists hope to trace antibodies, which the body develops to fend off the coronavirus and linger after it is gone.
The presence of those antibodies probably offers some protection against reinfection, although it is not yet known the extent to which people would be immune from the virus.
The research aims to fill in a number of blanks about COVID-19, including how deadly the disease truly is — a figure that is difficult to pin down without knowing how many people have the virus, said Neeraj Sood, a professor and vice dean for research at USC’s Price School of Public Policy, who worked with the county on the study.
At this point, the county reports a death rate of 2.8% of people with confirmed cases. By contrast, the average death rate of the seasonal flu is 0.1%
“If the mortality rate of COVID is 10 times that of the flu, then we should all be freaking out and we should be staying at home and making sure that we practice very strong physical distancing,†Sood said. “But if the true mortality rate of COVID is five times less than the flu, then we don’t need to be doing that. Then it is a less deadly disease.â€
Using antibody testing over time could also illuminate the effects of the aggressive physical distancing measures in Los Angeles and across most of the country — a step that has brought nearly all economic activity to a halt. If the rate of infection continues to climb in the population even with these measures in place, it may prompt politicians to rethink their usefulness in the face of massive job losses.
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Socially distanced bikers and walkers, against a backdrop of the Queen Mary, make their way along pedestrian and beach bike path on the first day that Long Beach reopened the path on Monday May 11, 2020. The city of Long Beach eased a few of its public health restrictions, allowing under certain guidelines the reopening of pedestrian and beach bike paths, tennis centers and courts. Beach bathrooms are also reopening, but the parking lots and beaches still remain closed. (Genaro Molina/Los Angeles Times)
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Traffic remains light on the southbound 110 Freeway headed toward downtown Los Angeles on April 28. (Robert Gauthier / Los Angeles Times)
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Dominique Barrett, center, known as “King Vader†to his 2.4 million TikTok followers, prepares to shoot a video on April 30 in Glendora. (Dania Maxwell / Los Angeles Times)
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Cody Purcell of Redondo Beach rides a wave, glowing from the bioluminescence, in Hermosa Beach, CA, after midnight Friday morning, May 8. (Jay L. Clendenin/Los Angeles Times)
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Friends play spikeball, a game perfect for social distancing on an open but restricted San Buenaventura State Beach. (Brian van der Brug / Los Angeles Times)
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The majority of golfers are wearing masks while hitting balls on the driving range at Van Buren Executive Golf Course in Riverside. (Gina Ferazzi / Los Angeles Times)
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Beaches including Harbor Cove Beach were open but beachgoers were not supposed to be sitting on the sand. (Brian van der Brug / Los Angeles Times)
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Tango instructor Yelizaveta Nersesova leads a Zoom tango event from her Los Angeles home April 27 that brought together hundreds of dancers from around the world. (Jason Armond / Los Angeles Times)
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Grocery store workers, joined by United Food and Commercial Workers International Union Local 770 representatives and community members, hold a rally in support of strict social distancing on May 1 at a Ralphs store in Hollywood where 19 employees have tested positive for COVID-19. (Kent Nishimura / Los Angeles Times)
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Mostly masked commuters keep their distance from one another on a Metro bus in downtown Los Angeles on April 29. (Gabriella Angotti-Jones / Los Angeles Times)
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Gregory Kuhl, 69, heads home after a shopping trip in Hollywood on April 28. Big cracks in the street, cars parked in driveways blocking sidewalks and uneven pavement levels make navigating his route difficult. (Dania Maxwell / Los Angeles Times)
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Tenants and their supporters from across Los Angeles gather at city hall to call on L.A. Mayor Eric Garcetti, the L.A. City Council and California Gov. Gavin Newsom to cancel rent and mortgage payments during the COVID-19 crisis. (Luis Sinco / Los Angeles Times)
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Aerial view of over 100 vehicles lined up at the West Valley COVID-19 testing center at Warner Center in Woodland Hills. (Brian van der Brug / Los Angeles Times)
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Senior Mason Wise, left, helps his sister, Mackenzie, a sophomore, clean out her PE locker at El Camino Real Charter High School in Woodland Hills. School officials were allowing no more than five students at a time on campus to take home their belongings. (Brian van der Brug / Los Angeles Times)
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Shuttered storefront businesses in the garment district of Los Angeles. California’s unemployment rate has skyrocketed since the statewide coronavirus shutdown took effect. (Luis Sinco / Los Angeles Times)
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Healthcare workers celebrate as Claudia Martinez is discharged from the ICU after she recovered from COVID-19 at Scripps Mercy Hospital in Chula Vista. (Marcus Yam / Los Angeles Times)
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Carson residents Kaeli Burks, 3, left, and her cousin Bailey Watson, 5, look out the window of their car after their mothers helped them with self-testing at a new drive-up testing site for COVID-19 in Carson. Free COVID-19 testing is available to all city residents thanks to a partnership between the city and US Health Fairs. (Genaro Molina / Los Angeles Times)
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Norm and Tracy Kahn enjoy eating dinner outside on a small cafe table sitting in blue chairs on their side yard during the coronavirus pandemic on April 27 in Riverside. “During this pandemic, eating outside offers us an opportunity to change surrounding and appreciate the calmness of being outdoors among trees, scents from nature and the sounds of birds,†she said. Also adding, “Mixing up where we eat puts variety into our days and takes away the sameness of feeling trapped at home.†(Gina Ferazzi / Los Angeles Times)
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Ronald Reagan UCLA Medical Center nurses carry supplies outside the hospital. (Robert Gauthier / Los Angeles Times)
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Tom Sean Foley pauses on a walk with his kids, Cathelen Claire, “C.C.,†3, and Timothy Joseph, 4, to take a photo in front of the “Love Wall,†mural by artist Curtis Kulig, outside of Smashbox Studios in Culver City. (Jay L. Clendenin / Los Angeles Times)
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Protesters stand along Mission Blvd. in Pacific Beach during A Day of Liberty rally on April 26. The protesters were against the government shutdown due to the coronavirus. (K.C. Alfred / San Diego Union-Tribune)
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People make orders at a food truck along Shoreline Avenue in Long Beach. (Luis Sinco / Los Angeles Times)
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Medical staff, wearing protective gear, work inside a COVID-19 isolation area inside the emergency department at Los Angeles County-USC Medical Center in Los Angeles, where patients with the virus are being treated. (Mel Melcon / Los Angeles Times)
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Neighbors practice social distancing while enjoying the nice weather near The Strand in Hermosa Beach. (Gabriella Angotti-Jones / Los Angeles Times)
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Counter-protesters attend a protest to call on state and local officials to reopen the economy in downtown Los Angeles. (Christina House / Los Angeles Times)
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A group of protesters cheer on cars during a vehicle caravan protest to call on state and local officials to reopen the economy in downtown Los Angeles. (Christina House / Los Angeles Times)
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Cedar Mountain Post Acute Rehabilitation staff member Navi Cavaltera waters a flower pot put up by the community to show their support for the nursing staff of the facility in Yucaipa. Eighteen of 20 coronavirus-related deaths in Yucaipa were residents of the skilled nursing facility. (Irfan Khan / Los Angeles Times)
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A pedestrian wearing a protective mask passes a mural on a store on Melrose Avenue in the Fairfax district of Los Angeles. (Allen J. Schaben / Los Angeles Times)
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Jonte Florence, a freestyle dancer, does a handstand on a mostly empty Hollywood Walk of Fame. Florence said he normally performs for hundreds of tourists along the busy street. (Allen J. Schaben / Los Angeles Times)
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The Tyrannosaurus rex overlooking the intersection of Hollywood Boulevard and Highland Avenue wears a protective mask while practicing social distancing. (Allen J. Schaben / Los Angeles Times)
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Businesses are shuttered and pedestrians are few and far between on Hollywood Boulevard. (Allen J. Schaben / Los Angeles Times)
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Daniel Rogerson wears a vintage military gas mask while riding a bike along the beach path in Santa Monica, which is closed to enforce social distancing because of the coronavirus pandemic. (Luis Sinco / Los Angeles Times)
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A face mask seller in colorful dress appears to be part of a mural behind a bus stop on Soto Street in Los Angeles. (Irfan Khan / Los Angeles Times)
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Life around Cesar E. Chavez Boulevard and Soto Street has slowed down as California officials extended stay-at-home orders into May and residents entered Easter weekend with unprecedented limits on their movements. (Irfan Khan / Los Angeles Times)
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UC Irvine Medical Center health care workers return their gratitude as about 25 Orange County first responder vehicles participate in a drive-by parade of gratitude as they battle COVID-19 at the hospital. (Allen J. Schaben / Los Angeles Times)
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Billy Budd, 55, of Hollywood, walks along Hollywood Boulevard with a protective face covering. Budd is a scenic artist for movies and television who is currently out of work due to the coronavirus outbreak. (Mel Melcon / Los Angeles Times)
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Stuart Reyes and his sister, Stephanie, sell masks for $5 each on the 3000 block of West Century Boulevard in Inglewood. Stuart Reyes said he is selling masks to support his mother. (Irfan Khan / Los Angeles Times)
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A jogger runs on a closed trail past dozens of pieces of caution tape, torn off by hikers and mountain bikers at El Escorpion Canyon Park in West Hills. (Brian van der Brug / Los Angeles Times)
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Alex Herron and nurse Mercy Pineda at a blood drive sponsored by USC athletics and the American Red Cross at USC’s Galen Center. (Genaro Molina / Los Angeles Times)
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Los Angeles City Hall displays blue lights to show support for healthcare workers and first responders. (Gary Coronado / Los Angeles Times)
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After being indoors for several days because of rainy weather and coronavirus stay-at-home orders, Olivia Jacobs, 4, and her mom, Cia Jacobs, enjoy a warm and sunny afternoon making chalk drawings on the sidewalk in front of their home in West Hills. (Brian van der Brug / Los Angeles Times)
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An Oceanview Plaza security guard sports a whimsical mask while on patrol. (Robert Gauthier / Los Angeles Times)
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Jacob De Wilde, left, and Lesli Lytle load a car with food during a food distribution organized to mark Good Friday. (Irfan Khan / Los Angeles Times)
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As a late season storm continues to make its way across the Southland, a young basketball player dribbles along an alley through an Elysian Park neighborhood in Los Angeles. (Kent Nishimura / Los Angeles Times)
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People are silhouetted in a window of an apartment building in Hollywood, where a stay-at-home order remains in effect to help curb the spread of the coronavirus. (Luis Sinco / Los Angeles Times)
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The Wilshire Grand Center display blue lights and a heart to show support for healthcare workers and first responders. (Gary Coronado / Los Angeles Times)
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Women wear masks as they stroll along Highland Avenue in Hollywood. Wearing masks while outdoors is mandatory in the city of Los Angeles. (Luis Sinco / Los Angeles Times)
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Patients are removed from Magnolia Rehabilitation and Nursing Center after 39 tested positive for the coronavirus and nursing staff was not showing up to work. (Gina Ferazzi / Los Angeles Times)
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A specimen is turned in at the new mobile testing site for people with symptoms of the coronavirus at Charles R. Drew University of Medicine and Science in South Los Angeles. (Christina House / Los Angeles Times)
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Hippie Kitchen in Los Angeles hands out food, water and toiletries to homeless people and residents of skid row. Additionally, masks were offered to help reduce the spread of the coronavirus. (Myung J. Chun / Los Angeles Times)
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Nurses pose for a fun photo during a break in drive-through public testing for the coronavirus at Arrowhead Regional Medical Center in Colton. (Irfan Khan / Los Angeles Times)
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A woman shows a notice from her doctor that allows her to obtain a test for coronavirus at a new drive-up testing site in a parking lot at the South Bay Galleria in Redondo Beach. (Genaro Molina / Los Angeles Times)
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A person who wishes to remain anonymous strikes from her car to support McDonald’s employees who are demanding the company cover healthcare costs of any worker or immediate family member who gets sick from COVID-19 in Los Angeles. (Dania Maxwell / Los Angeles Times)
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Cassidy Roosen, with Beach Cities Health District, holds up a sign that says, “We’re All in This Together,†while waiting to direct cars at a drive-through, appointment-only coronavirus testing location at the South Bay Galleria in Redondo Beach. (Jay L. Clendenin / Los Angeles Times)
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Grace Carter, 15, of Riverside, practices a dance routine at home after dance classes and school were canceled. She has to use the Zoom app on her iPhone to practice with her dance group. “It’s hard,†she said. “My bedroom is a smaller space. I miss all my friends at the studio.†(Gina Ferazzi / Los Angeles Times)
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A man works from his home in Long Beach. (Marcus Yam / Los Angeles Times)
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A San Bernardino County healthcare worker takes a sample at a coronavirus drive-through testing site at the county fairgrounds in Victorville. (Irfan Khan / Los Angeles Times)
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A Metro general service employee disinfects a bench in Boyle Heights. (Gary Coronado / Los Angeles Times)
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A runner jogs past the Pottery Barn in Pasadena. Some businesses in the area have boarded up their stores. (Al Seib / Los Angeles Times)
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Raquel Lezama and daughter Monica Ramos collect meals for their family at Manual Arts High School. Lezama was laid off from her $17.76-an-hour job at a Beverly Hills hotel. (Al Seib / Los Angeles Times)
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The Iron City Tavern in San Pedro tries an incentive to lure takeout customers. (Carolyn Cole / Los Angeles Times)
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Healthcare workers gather outside UCLA Ronald Reagan Medical Center to call for further action from the federal government in response to the COVID-19 outbreak. (Robert Gauthier / Los Angeles Times)
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Kristen Edgerle, of Victorville, collects information from a blood donor before drawing blood at The Richard Nixon Presidential Library blood drive during the coronavirus pandemic in Yorba Linda. (Jason Armond / Los Angeles Times)
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Shauna Jin, of Los Angeles, with her dog, Bodhi, practices social distancing with John Kiss, of Los Angeles, at the entrance of Runyon Canyon Park in Los Angeles. (Gary Coronado / Los Angeles Times)
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A lending library had some additional useful items, including a roll of toilet paper and cans of beans and corn, in a Hermosa Beach neighborhood. (Jay L. Clendenin / Los Angeles Times)
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Protesters drive by the Getty House, the home of L.A. Mayor Eric Garcetti, in Hancock Park. Tenant advocates are demanding a total moratorium on evictions during the coronavirus crisis. (Wally Skalij / Los Angeles Times)
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Venice residents Emily Berry and Gavin Kelley take a break at Venice Beach. Berry, a cocktail waitress at Enterprise Fish Co., lost her job due to the coronavirus outbreak. Kelley, a manager at a performing arts school with a focus on music, said that he still has a job and that classes at the school will resume online this coming Monday. (Mel Melcon / Los Angeles Times)
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The JW Marriott at L.A. Live is sharing a message of hope with red lights in 34 windows, creating a 19-story display on the hotel’s north side. (Gary Coronado / Los Angeles Times)
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Juan Diaz Jr., a lifelong Dodgers fan, prays that the season will start by May in front of Dodger Stadium on what would have been opening day. (Mel Melcon / Los Angeles Times)
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Hayley, CEO and founder of Love My Neighbor Foundation, right, dances with Crystal Armster, 51, while she and her colleagues continue to feed the homeless on skid row amid the pandemic. (Genaro Molina / Los Angeles Times)
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A masked passenger on a Metro bus in downtown Los Angeles. (Wally Skalij / Los Angeles Times)
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Dede Oneal waits for a coronavirus test at the Crenshaw Christian Center in South Los Angeles. (Genaro Molina / Los Angeles Times)
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A man in a mask passes a closed restaurant along Spring Street in downtown Los Angeles. (Wally Skalij / Los Angeles Times)
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Artist Corie Mattie paints a mural on the side of a pop-up store as a man takes a picture in West Hollywood. (Wally Skalij / Los Angeles Times)
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Medical assistant Zoila Villalta works with Rosie Boston, 32, of Glendale, who is donating blood for her first time at L.A. Care Health Plan downtown. (Al Seib / Los Angeles Times)
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A couple wait for a bus outside the Petersen Automotive Museum in Los Angeles. (Luis Sinco / Los Angeles Times)
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With all Los Angeles schools closed until further notice, LAUSD buses sit idle in Gardena. (Brian van der Brug / Los Angeles Times)
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A lone traveler makes his way to catch a flight in Tom Bradley International Terminal. (Genaro Molina / Los Angeles Times)
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Denise Young looks on as her daughter, Allison, 9, a fourth-grader at EARThS (Environmental Academy of Research Technology and Earth Sciences) Magnet School in Newbury Park, receives a Chromebook. (Mel Melcon / Los Angeles Times)
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Hollywood Boulevard is devoid of the usual crowds. (Brian van der Brug / Los Angeles Times)
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Michael Ray, 11, plays before a movie at the Paramount Drive-In. (Wally Skalij / Los Angeles Times)
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Isabella Leader, 15, counts how many flags have been left for World War II veteran Lt. Col. Sam Sachs who was celebrating his 105th birthday at the Mom & Dad’s House, an assisted living facility, in Lakewood. Lt. Col. Sachs appealed to the public for birthday cards after the coronavirus pandemic forced the cancellation of a big celebration and wound up receiving thousands, including a letter and photo from President Trump. (Genaro Molina / Los Angeles Times)
Additionally, the tests could offer clues as to when at least 60% of the population has at one point been infected, achieving “herd immunity,†which would significantly thwart the spread of the virus.
Experts caution that serological testing is not a panacea. It is still unclear how much immunity a person has from the coronavirus when antibodies are present. And the surge of new tests coming to the market means there is a wide variance in accuracy and reliability.
This week, Oxford University researchers found that at-home blood tests used in the U.K. were faulty, after the British government had ordered more than 4 million of such tests for residents.
“There are a lot of unknowns,†said Kevin de León, a former state Senate leader and incoming L.A. city councilman who has helped with the L.A. study’s launch. “However, we have this opportunity to scientifically determine whether there are those among us who can reenter the workforce safely, and we’ve got to seize it.â€
So far, it has been impossible to quantify how many people have had the virus, because of a shortage of nasal swab test kits. The dearth of information threatened to hamper hospitals’ ability to prepare for the virus last month, as the wave of cases began to swell.
“I felt that we were flying blind,†said Dr. Brad Spellberg, chief medical officer at Los Angeles County-USC Medical Center. “We had no idea what was going on in the community around us.â€
In mid-March, he decided to perform nasal swab tests on roughly 130 patients who came to his center’s emergency room and urgent care with mild flu-like symptoms. It offered a glimpse into a population beyond the highest-risk, most severe cases that have been the main focus of testing so far. He found that 5.3% of the patients with milder symptoms tested positive for COVID-19, a result he called “alarming.â€
“These were young, active people,†Spellberg said. “They were going to work. They were going to community events. They had no idea that they had coronavirus and they had the real potential to be spreading this.â€
Spellberg said the results pushed him to escalate his planning for needed personal protective equipment and hospital beds. The county also took notice.
Gov. Gavin Newsom has repeatedly said California needs to expand beyond diagnostic tests of sick patients to understand the virus.
At a news conference Thursday, Newsom said antibody blood tests are “critical in terms of our capacity to make a determination about community spread and about immunity.â€
The governor has said testing broader samples of the public throughout the state, not just people exhibiting COVID-19 symptoms, will help officials determine when to lift the stay-at-home order. But that kind of testing is occurring only at the local level or at universities.
The blood testing conducted last week in Santa Clara County involved participants who were found via social media.
“This was the first-of-a-kind, large attempt to measure how many people in a large county have been infected,†said Eran Bendavid, a specialist in infectious disease and professor at the Stanford Health Policy program, who is leading the project in conjunction with the county public health office.
The first round of results, which have been collected but not yet published, makes clear that many people have been infected and are not showing symptoms, Bendavid said.
Stanford University on Wednesday also began offering widespread serology testing to anyone who wants it. Dr. James Zehnder said that the university medical system has the capacity to perform up to 750 serology tests a day and expects to increase capacity soon.
Currently, Zehnder said, there is no backlog of testing and rules have been relaxed so that any person who wants a diagnostic or serology test can be accommodated.
In Los Angeles, the research team will stage six drive-through testing sites throughout the county Friday and Saturday. Participants were invited through a marketing firm to create a random sample that mirrors the demographic makeup of the county, in order to best allow the data to be extrapolated to apply to the county as a whole.
The kit functions somewhat like a pregnancy test. Participants supply a drop of blood via pinprick; when combined with a buffer solution, a number of lines appear to indicate the presence of certain antibodies. Simon, the L.A. County chief science officer, said that individuals can get their results on an online portal within 24 hours and that the county would make its analysis of the data publicly available late next week.
The antibody tests were secured by Sood for free through a donor. The marketing firm Lieberman Research Worldwide is working pro bono. Some funding and logistical support is coming from the USC Schwarzenegger Institute for State and Global Policy and officials are raising money from private donors to repeat the study every two weeks for three months, which Simon estimated would cost at least $1.1 million.
Times staff writers Anita Chabria and Taryn Luna in Sacramento contributed to this report.
